Migrate EE approval selectors to testid

What does this MR do and why?

Migrates some data-qa-selector attributes to be data-testid as per gitlab-org/quality/quality-engineering/team-tasks#1822 (closed)

How to set up and validate locally

Test affected E2E spec:

CHROME_HEADLESS=false bundle exec bin/qa Test::Instance::All http://gdk.test:3000/ ./qa/specs/features/shared_examples/merge_with_code_owner_shared_examples.rb

Test affected feature spec:

yarn jest ee/spec/frontend/approvals/components/approval_settings/approval_settings_checkbox_spec.js

Also note results of Allure reports, should be passing / known unrelated failures.

MR acceptance checklist

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