Merge branch 'non-null-constraint-for-noteable-type' into 'master'

Add non-null constraint to notes table for noteable_type column

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143918



Merged-by: Diogo Frazão <dfrazao@gitlab.com>
Approved-by: Abdul Wadood <awadood@gitlab.com>
Approved-by: David Dieulivol <ddieulivol@gitlab.com>
Approved-by: Diogo Frazão <dfrazao@gitlab.com>
Co-authored-by: Eulyeon Ko <eko@gitlab.com>