Reduce repository code by implementing top five

Identify top 5 opportunities to massively reduce the amount of code (lines of code) in any part of the repo: - Similar functionality that can be unified and reused - Code that has been valuable but no more - A front end component or a group of them duplicate another component/page functionality. Use the most modern and nice looking - etc. Now implement them :)

Implemented the five measured code-reduction folds (TaskFieldDialog shell, run_as_session_user_or_here, dashboard clockTime, _owner_sid, nodevault _flush_operation + selftest_runner.report): 18 files, net −42 lines, 14 copies folded. Quick gate pass; review + verifier lanes pass. PR #7462 queued in the merge lane. Assumed "massively" means the most the repo can lose without behaviour change; larger candidates measured and rejected (in report). Memory: none applied.