Revert "Merge branch 'allow-secure-files-bucket-optional' into 'master'"

What does this MR do and why?

This reverts !131819 (merged) because this can cause consolidated settings to be disabled since ci_secure_files_object_store_connection is set on GitLab.com.

We can avoid this by allowing consolidated settings to operate if the connection doesn't differ from the global settings, but let's revert this for now.