Merge branch 'delete-old-feature-flags-zoekt_random_force_reindexing' into 'master'

Delete the `zoekt_random_force_reindexing` feature flag

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182555



Merged-by: Arturo Herrero <arturo.herrero@gmail.com>
Approved-by: Arturo Herrero <arturo.herrero@gmail.com>
Co-authored-by: Siddharth Dungarwal <sdungarwal@gitlab.com>