Remove parse_ci_job_timestamps feature flag

What does this MR do and why?

This MR removes the parse_ci_job_timestamps feature flag, to add support for parsing CI log timestamps. The FF was enabled on staging on June 5th, and on prod on June 7th 9:51 UTC. We'll leave it over the Friday+weekend and then merge this.

Changelog: added

Part of #464785 (closed)

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