Fix link in plain-text re-request MR review mails

What does this MR do and why?

Tiny follow-up to Added backend for requesting a new review (!52321 - merged)

In the plain-text email template merge_request_reference_link() was used, which outputs the HTML link – not just the raw URL. This causes weirdness in some email clients.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Disable multipart emails
2. Re-request review on an MR
3. Observe HTML output in plaintext email

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.

changed milestone to %16.7

added bugux groupcode review severity4 typebug labels

assigned to @manuelgrabowski

added devopscreate sectiondev labels

added Support Team Contributions label

added backend frontend labels

	1 Warning
	You've made some app changes, but didn't add any tests. That's OK as long as you're refactoring existing code, but please consider adding any of the maintenancepipelines, maintenancerefactor, maintenanceworkflow, documentation, QA labels.

	1 Message
	CHANGELOG missing: If this merge request needs a changelog entry, add the Changelog trailer to the commit message you want to add to the changelog. 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	@hustewart (UTC-5)	@pskorupa (UTC+1)
frontend	@psjakubowska (UTC+1)	@leipert (UTC+1)

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Generated by Danger

requested review from @leipert

Allure report

allure-report-publisher generated test report!

e2e-test-on-gdk: test report for e7f3e658

expand test summary

+-----------------------------------------------------------------------+
|                            suites summary                             |
+------------------+--------+--------+---------+-------+-------+--------+
|                  | passed | failed | skipped | flaky | total | result |
+------------------+--------+--------+---------+-------+-------+--------+
| Data Stores      | 23     | 0      | 0       | 0     | 23    | ✅     |
| Govern           | 57     | 0      | 0       | 0     | 57    | ✅     |
| Verify           | 31     | 0      | 0       | 0     | 31    | ✅     |
| Plan             | 55     | 0      | 0       | 0     | 55    | ✅     |
| Create           | 48     | 0      | 9       | 0     | 57    | ✅     |
| Monitor          | 8      | 0      | 0       | 0     | 8     | ✅     |
| Framework sanity | 0      | 0      | 1       | 0     | 1     | ➖     |
| Package          | 0      | 0      | 1       | 0     | 1     | ➖     |
| Manage           | 0      | 0      | 1       | 0     | 1     | ➖     |
+------------------+--------+--------+---------+-------+-------+--------+
| Total            | 222    | 0      | 12      | 0     | 234   | ✅     |
+------------------+--------+--------+---------+-------+-------+--------+

e2e-package-and-test: test report for e7f3e658

expand test summary

+-------------------------------------------------------------+
|                       suites summary                        |
+--------+--------+--------+---------+-------+-------+--------+
|        | passed | failed | skipped | flaky | total | result |
+--------+--------+--------+---------+-------+-------+--------+
| Create | 527    | 0      | 48      | 0     | 575   | ✅     |
+--------+--------+--------+---------+-------+-------+--------+
| Total  | 527    | 0      | 48      | 0     | 575   | ✅     |
+--------+--------+--------+---------+-------+-------+--------+

approved this merge request

@leipert, thanks for approving this merge request.

This is the first time the merge request has been approved. To ensure we don't only run predictive pipelines, and we don't break master, a new pipeline will be started shortly.

Please wait for the pipeline to start before resolving this discussion and set auto-merge for the new pipeline. See merging a merge request for more details.

added pipeline:mr-approved label

resolved all threads

enabled an automatic merge when the pipeline for 79c144a2 succeeds

Thanks @manuelgrabowski!

merged

mentioned in commit ee7adf71

added workflowstaging-canary label

added workflowcanary label and removed workflowstaging-canary label