Adjust severity Icon to change when expanded

What does this MR do and why?

This MR solves: #366643 (closed)

It adjusts the severity icon to change to the collapse icon when the codequality inline-diff is expanded.

Screenshots or screen recordings

before	after
before-indicator	2022-09-06_18-43-11

How to set up and validate locally

1. make sure your GDK has an ultimate license
2. Feature.enable(:refactor_code_quality_inline_findings)
3. clone this project: https://gitlab.com/jannik_lehmann/code-quality-test
4. recreate this MR: http://gdk.test:3000/root/code-quality-test-index/-/merge_requests/1
5. run pipeline
6. See inline diffs in diff view of created MR

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.