Update setting wording to be more concise

What does this MR do and why?

Update setting wording to be more concise

• update it to match policy scope wording

References

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Upload a GitLab Ultimate license
2. Enable the feature flag echo "Feature.enable(:scan_result_policy_block_group_branch_modification)" | rails c
3. Navigate to a group => Secure => Policies => New policy => Merge request approval policy
4. Verify the Block group branch modification setting is similar to policy scope

Related to #500842 (closed)