Revert "Merge branch '371986-introduce-ff' into 'master'"

What does this MR do and why?

Describe in detail what your merge request does and why.

Reverts !98683 (merged) because it's causing a broken master to close #375620 (closed)

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. bin/rspec spec/frontend/fixtures/timezones.rb spec/frontend/fixtures/pipeline_ schedules.rb
2. yarn run jest spec/frontend/ci_variable_list/ci_variable_list/ci_variable_list_spec.js spec/frontend/pages/projects/pipeline_schedules/shared/components/timezone_dropdown_spec.js spec/frontend/ci_variable_list/ci_variable_list/native_form_variable_list_spec.js

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.