Introduce new jobs tab - clean up feature flag

What does this MR do and why?

Let's wait to merge this until 2/22/22

This MR cleans up the jobs_tab_vue feature flag. Target date to merge this MR should be after the release of 14.8

MRs that are related

Implementation: !76146 (merged)

Specs: !76972 (merged)

Screenshots or screen recordings

How to set up and validate locally

1. Visit the jobs tab on any pipeline
2. Confirm everything is working as expected after the cleanup

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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