Run jest full specs when frontend and feature flag label are applied

What does this MR do and why?

This MR runs jest full specs automatically when the frontend feature flag labels are applied to the merge requests.

Closes #375663 (closed)

Testing

Tested changes on !99189 (closed).

File Change	Result
frontend feature flag label (ada7e81e)	✅ jest job are created: https://gitlab.com/gitlab-org/gitlab/-/pipelines/670429412
frontend label (946dfe37)	✅ jest minimal jobs are created: https://gitlab.com/gitlab-org/gitlab/-/pipelines/653587124

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

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

MR acceptance checklist

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