Merge branch 'sh-drop-datamapper-attr-encrypted' into 'master'

Drop support for DataMapper in attr_encrypted

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143702



Merged-by: Thong Kuah <tkuah@gitlab.com>
Approved-by: Thong Kuah <tkuah@gitlab.com>
Co-authored-by: Stan Hu <stanhu@gmail.com>