Merge branch 'auth/gb/return-not-allowed-for-composite-identity' into 'master'

Do not depend on exceptions in composite identity code

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/175054



Merged-by: Fabio Pitino <fpitino@gitlab.com>
Approved-by: Fabio Pitino <fpitino@gitlab.com>
Co-authored-by: Grzegorz Bizon <grzesiek.bizon@gmail.com>