In bf18e8f814, `buttons_context_compute()` was moved "upstream" in code
path, as a de-duplication effort. But this wasn't correct, because
function `property_search_for_context()` was executed in a loop where
the tabs were iterated over.
This commit moves `property_search_for_context()` back where it was
before.
Pull Request: https://projects.blender.org/blender/blender/pulls/137576