E2E test: repo settings data-testid migration

What does this MR do and why?

Part of gitlab-org/quality/quality-engineering/team-tasks#1825 (closed)

Migrates data-qa-selectors to data-testid for the following page object files used in the E2E tests: qa/qa/page/group/settings/repository.rb qa/qa/page/repository/settings/repository.rb

Fixes one method signature comment.

How to set up and validate locally

Since this affects many E2E tests, probably best to validate using pipeline results.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.