Pass issue ID to merge request creation form

What does this MR do and why?

After the change !79227 (merged) the merge request creation form loses context of the issue it was created from when a custom branch name is used

This change adds an ability to retain the issue IID context throughout the process so the text 'Closes #IssueIID' appears on the merge request regardless of how the branch was created (automatic name or custom name)

This brings back the feature of related merge requests and system notes on the issue that went absent after the change above

Screenshots or screen recordings

N/A

How to set up and validate locally

  1. Create an issue under any project
  2. Visit the issue and click dropdown next to Create merge request button
  3. Enter a simple custom branch such as abcd
  4. Prior to patch: New MR creation form lacked pre-filled description text Closes #1
  5. After patch: New MR creation form has pre-filled description text Closes #1

MR acceptance checklist

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

Closes #352304 (closed) Related to #353694

Edited by Harsh Chouraria