…6486)

* Make the number of reusable blocks returned from the API unlimited

This is to fix #26352. Having no limit seems like it could be risky, but
there are a number of other places in the codebase where all entities
are returned in one call to the API, including categories, which could
return a similar amount of data to this.

* Remove unnecessary quotes to fix lint error.

* fix heading alignments

* add proper supports in deprecation

* update all previous deprecations

* regenerate fixtures for heading

* change migration call

* remove previous className + revert saves

* Revert "regenerate fixtures for heading"

This reverts commit 27af8c3.

* change fixtures

* create new fixtures + fix deprecation save

* address review feedback

Wait until the user finishes typing before sending an AJAX request. This
ensures that there isn't an AJAX request sent every 200 ms while the
user is typing.

If there is only one column, don't force a 50% flex-basis for small screens.

* Change block mover label i18n

* Update remove block i18n