Fix merge requests not importing for older projects

See merge request gitlab-org/gitlab!74031

This restores the merge request commit user fields in import_export.yml
for the import case.

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/73307 dropped
these YAML fields because supposedly the import would fail if the
database columns didn't exist, but I haven't found that to be the
case. I tested with an import with:

1. Project generated in v13.12 that had these columns.
2. Project generated with the latest nightly build.

The import works in either case because we call
`MergeRequestDiffCommit.new` with the sanitized attributes in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/73307.

Based on the discussion in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/72219, these
attributes are needed for **import** but excluded for **export**. I
think Yorick might have assumed that since the code in
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/73307 manually
removed these fields, we wouldn't need them anymore. However, without
these attributes, imports were failing to import with an older GitLab
version (e.g. v13.12) because the attributes were sanitized before the
importer got a chance to use them.

Changelog: fixed

Update gitlab-dangerfiles to 2.5.0

See merge request gitlab-org/gitlab!73971

Updated release:name to standards

See merge request gitlab-org/gitlab!74029

Update pipelines api docs

See merge request gitlab-org/gitlab!73795

Fix issue rebalance banner

See merge request gitlab-org/gitlab!73608

Change the copy and empty state illustrations in the Kubernetes section

See merge request gitlab-org/gitlab!73586

Show blocked icon on epic blocked issues

See merge request gitlab-org/gitlab!72229

Add parsed YAML is too big section

See merge request gitlab-org/gitlab!73768

Clarify loss of DAG behavior with `needs:pipeline`

See merge request gitlab-org/gitlab!73622

Added comment to clarify that none of the items are used in the docs

See merge request gitlab-org/gitlab!74020

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/343854

Restore the BackgroundMigration.remaining method

See merge request gitlab-org/gitlab!74015

Refactor fetching board scope to GraphQL [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!73604

Changelog: changed
EE: true

Signed-off-by: Rémy Coutable <remy@rymai.me>

Doc custom image in Auto Deploy

See merge request gitlab-org/gitlab!73605

Doc Consistency: user/compliance - composition analysis

See merge request gitlab-org/gitlab!72922

Doc Consistency: user/compliance - compliance

See merge request gitlab-org/gitlab!72921

Update declarative_policy to v1.1.0

See merge request gitlab-org/gitlab!73831

Add project rules based on scan result policies

See merge request gitlab-org/gitlab!70633

Audit Event Streaming

See merge request gitlab-org/gitlab!73149

Remove unnecessary sections from Lean template

See merge request gitlab-org/gitlab!73623

Add blank Project Quality tab to project CI/CD analytics

See merge request gitlab-org/gitlab!72724

Blank placeholder tab for now
Only show it if the licensed feature is available
and the feature flag is enabled

Remove the logic hardcoding iteration dates in title

See merge request gitlab-org/gitlab!72846

Filter runner type via tabs

See merge request gitlab-org/gitlab!73680

Make sure CI job `db:check-schema` can catch corrupted `structure.sql`

See merge request gitlab-org/gitlab!73298

Allow "control" and "candidate" function names

See merge request gitlab-org/gitlab!73718

Make `/features` API accept percentage as float to enable 0.01%

See merge request gitlab-org/gitlab!73965

merge_request_diff.rb: Populate CommitCollection from target project/branch

See merge request gitlab-org/gitlab!67016

Remove variable_inside_variable feature flag

See merge request gitlab-org/gitlab!73662