Fix reference to groupApprovers in security approvals

What does this MR do and why?

Addresses #422609 (closed)

Fix reference to groupApprovers in security approvals

This change fixes a bug caused by using groupApprovers instead of allGroupApprovers in approval rules settings page which was introduced in !128013 (merged).

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Create a scan result policy for a project
• Go to Settings -> Merge requests and go to Security Approvals section and notice that the section shows the approvals from scan result policy

MR acceptance checklist

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