Added service to find target branch rule branch

What does this MR do and why?

Creates the service that searches and returns the target branch rule target for the specified branch name. If the rule doesn't exist or then the default branch name will get returned.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

#17909 (closed)

changed milestone to %16.3

added backend devopscreate featureaddition groupcode review typefeature labels

assigned to @iamphill

changed the description

added feature flag label

	1 Warning
	featureaddition and featureenhancement merge requests normally have a documentation change. Consider adding a documentation update or confirming the documentation plan with the Technical Writer counterpart. For more information, see: The Handbook page on merge request types. The definition of done documentation.

	1 Message
	CHANGELOG missing: If you want to create a changelog entry for GitLab FOSS, add the Changelog trailer to the commit message you want to add to the changelog. If you want to create a changelog entry for GitLab EE, also add the EE: true trailer to your commit message. If this merge request doesn't need a CHANGELOG entry, feel free to ignore this message.

Reviewer roulette

Changes that require review have been detected!

Please refer to the table below for assigning reviewers and maintainers suggested by Danger in the specified category:

Category	Reviewer	Maintainer
backend	Pam Artiaga (@partiaga) (UTC+10, 9 hours ahead of @iamphill)	Jessie Young (@jessieay) (UTC+9, 8 hours ahead of @iamphill)

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• Reviewer is unavailable!

Feel free to override these selections if you think someone else would be better-suited or use the GitLab Review Workload Dashboard to find other available reviewers.

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Generated by Danger

mentioned in commit gitlab-org-sandbox/gitlab-jh-validation@0a016202

Allure report

allure-report-publisher generated test report!

e2e-test-on-gdk: test report for f2f1381a

expand test summary

+------------------------------------------------------------------+
|                          suites summary                          |
+-------------+--------+--------+---------+-------+-------+--------+
|             | passed | failed | skipped | flaky | total | result |
+-------------+--------+--------+---------+-------+-------+--------+
| Create      | 46     | 0      | 1       | 2     | 47    | ❗     |
| Govern      | 34     | 0      | 0       | 0     | 34    | ✅     |
| Plan        | 47     | 0      | 0       | 0     | 47    | ✅     |
| Manage      | 12     | 0      | 1       | 0     | 13    | ✅     |
| Verify      | 8      | 0      | 0       | 0     | 8     | ✅     |
| Data Stores | 20     | 0      | 0       | 0     | 20    | ✅     |
+-------------+--------+--------+---------+-------+-------+--------+
| Total       | 167    | 0      | 2       | 2     | 169   | ❗     |
+-------------+--------+--------+---------+-------+-------+--------+

e2e-package-and-test: test report for 0ca3d844

expand test summary

+-------------------------------------------------------------+
|                       suites summary                        |
+--------+--------+--------+---------+-------+-------+--------+
|        | passed | failed | skipped | flaky | total | result |
+--------+--------+--------+---------+-------+-------+--------+
| Create | 256    | 12     | 34      | 12    | 302   | ❌     |
+--------+--------+--------+---------+-------+-------+--------+
| Total  | 256    | 12     | 34      | 12    | 302   | ❌     |
+--------+--------+--------+---------+-------+-------+--------+

added sectiondev label

deleted the ph/targetBranchRulesDB branch. This merge request now targets the master branch

added database databasereview pending documentation labels

added Data WarehouseImpact Check label

added 3666 commits

• 139f2cf3...d6536379 - 3665 commits from branch master
• f80c6ca9 - Added service to find target branch rule branch

Compare with previous version

added 3666 commits

• 139f2cf3...d6536379 - 3665 commits from branch master
• f80c6ca9 - Added service to find target branch rule branch

Compare with previous version

mentioned in commit gitlab-org-sandbox/gitlab-jh-validation@0012e378

removed database databasereview pending labels

added 1 commit

• 0ca3d844 - Added service to find target branch rule branch

Compare with previous version

mentioned in commit gitlab-org-sandbox/gitlab-jh-validation@efb58954

added 373 commits

• 0ca3d844...f78928ed - 372 commits from branch master
• ac2cb2fc - Added service to find target branch rule branch

Compare with previous version

@iamphill Some end-to-end (E2E) tests have been selected based on the stage label on this MR.

Please start the trigger-omnibus-and-follow-up-e2e job in the qa stage and ensure the tests in follow-up-e2e:package-and-test-ee pipeline are passing before this MR is merged. (The E2E test pipeline is computationally intensive and we cannot afford running it automatically for all pushes/rebases. Therefore, this job must be triggered manually after significant changes at least once.)

If you would like to run all E2E tests, please apply the pipeline:run-all-e2e label and trigger a new pipeline. This will run all tests in e2e:package-and-test pipeline.

The E2E test jobs are allowed to fail due to flakiness. For the list of known failures please refer to the latest pipeline triage issue.

Once done, please apply the emoji on this comment.

For any questions or help in reviewing the E2E test results, please reach out on the internal #quality Slack channel.