Pull Request for Issue #33368, alternative for #33372

Summary of Changes

This PR modifies code so that the field contexts filter will only be displayed if there are more than one option. Compare to #33372, it also remove the unnecessary mark up, so it is a bit better.

Testing Instructions

1. Apply patch
2. Go to Content -> Fields, Content -> Field Groups, make sure you still see contexts filter (contains Articles, Category).
3. Go to Users -> Fields, Users -> Field Groups, make sure you do not see the filter anymore (before, the filter only contains on option Users ,so it is useless)
4. Go to Users -> Fields, view source of the page, make sure you don't see the useless mark up which @Quy mentioned here [4.0] Remove users dropdown in fields and field-groups #33372 (comment)