Merge branch 'add_not_null_constraint_to_epics_issue_id_2' into 'master'

Add epics.issue_id NOT NULL constraint

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/151791



Merged-by: Kassio Borges <kborges@gitlab.com>
Approved-by: Mario Celi <mcelicalderon@gitlab.com>
Approved-by: Omar Qunsul <oqunsul@gitlab.com>
Approved-by: Kassio Borges <kborges@gitlab.com>
Reviewed-by: Nicolas Dular <ndular@gitlab.com>
Reviewed-by: Doug Stull <dstull@gitlab.com>
Co-authored-by: Mario Celi <mcelicalderon@gitlab.com>
Co-authored-by: Eugenia Grieff <egrieff@gitlab.com>