We removed the last usage in D6103, but didn't remove the function itself. The new version of Flow wanted me to add typehints, but instead I'm just going to delete the function since it's not used.
NOTE: CI will fail on this diff. I considered the possibility of fixing Flow errors BEFORE upgrading Flow, but it wasn't possible... in some cases, the fixes to support the new version of Flow caused errors in the old version. I could have hidden these type errors with $FlowFixMe lines and then later revert those, but that seemed like too much busy work.
Depends on D10002