Collapse approval rules and move it under reviewer

MR	Changes
Part 1: !47976 (merged)	Create suggested approvers as a partial so it can be reused
Part 2: 👉 current	FE implementation of collapsing Approval Rules under Reviewers

What does this MR do?

This MR move the Approval Rules inside a collapsed format

Collapse	Expanded	FF off

Testing Case

This feature is behind 2 feature flag, to turn on:

rails c

Feature.enable(:merge_request_reviewers)
Feature.enable(:mr_collapsed_approval_rules)

Edit MR

1. Select a Merge Request and click "Edit"

• The approvals are now hidden within the collapse:

Collapse	Expanded

Create MR

1. The same effect is the same when you create a "New" Merge Request 👆

Not collapsed

This is the scenario when approval rules is in a collapsed format:

FF	Is Collapsed?
merge_request_reviewers True mr_collapsed_approval_rules = True	Yes
merge_request_reviewers False mr_collapsed_approval_rules = False	No
merge_request_reviewers True mr_collapsed_approval_rules = False	No
merge_request_reviewers False mr_collapsed_approval_rules = True	No

This is how it will appear when approval rules are no longer hidden. You can disable by:

rails c

Feature.disable(:merge_request_reviewers)
Feature.disable(:mr_collapsed_approval_rules)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #231244 (closed)