Remove feature flag `ci_reset_skipped_jobs_in_atomic_processing`

What does this MR do and why?

This MR removes the feature flag ci_reset_skipped_jobs_in_atomic_processing which was globally rolled out on 2023-06-21.

Context: As discovered in #388539 (closed), a race condition sometimes occurs during pipeline processing, which results in some dependent jobs remaining skipped after clicking the "Play all manual" button. A simplified visual workflow of what is happening can be found here. This feature fixes this condition by re-running ResetSkippedJobsService on any jobs change from a "stopped" status to an "alive" status during pipeline processing.

Roll out issue: #410203 (closed)

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.

Related to #410203 (closed)