If the file doesn't exist, the HEAD request will return a 403. We should
notify the user of this state rather than throw up a 500 page.

Move common code into ImportExportUpload model.

Now that the project export status in the database may be updated before
the upload has transferred to object storage, we should inform the user
that the export is still not available. We do this when the user
attempts to request the actual download since the existence check
requires a HEAD request to ensure the file is present.

When large exports were generated, we saw in production that these files
often were uploaded to object storage but were missing the relevant
`import_export_uploads` database entry. This was happening because the
idle in transaction timeout killed the database transaction.

CarrierWave v1, which we run now, will idle in transaction while saving
a file to object storage. CarrierWave v1 saves the file in the
`after_save` callback. From the database perspective, this begins a
transaction, inserts an entry into `import_export_uploads`, and then
attempts to upload the file to object storage. However, this quickly
runs into our 60-second idle-in-transaction timeout.

CarrierWave v2 tried to fix this in
https://github.com/carrierwaveuploader/carrierwave/pull/2209 by moving
the object storage save in the `after_commit` callback. This means the
object would only be uploaded after the database COMMIT, but this
presents other problems. For example, the file may appear to be
available even though it hasn't finished uploading to object storage.

CarrierWave v3, which has not yet released, will revert back to the v1
behavior via
https://github.com/carrierwaveuploader/carrierwave/pull/2546 with a
twist: if the transaction is rolled back for reason, CarrierWave will
delete the file in object storage.

For project exports, the v2 issues aren't a big deal since we don't need
to read the value after save, but this does mean the actual file may not
appear until some time after the database entry has been committed. This
means that the UI might display that a project export is available even
though it hasn't finished uploading, resulting in a 404. To avoid that,
we might want to call `file.exist?`, but this would require an HTTP HEAD
request.

Relates to:

* https://gitlab.com/gitlab-com/gl-infra/production/-/issues/4814
* https://gitlab.com/gitlab-org/gitlab/-/issues/195981

Changelog: fixed

Add level four heading option to headings dropdown in the Content Editor

See merge request gitlab-org/gitlab!63639

Adjust Button Sizes on Secure MR Widget

See merge request gitlab-org/gitlab!63407

Update Pipeline Artifact docs - clarify deletion / management section

See merge request gitlab-org/gitlab!62708

Document java 16 support for maven

See merge request gitlab-org/gitlab!63595

Remove ExecuteHooksWorker

See merge request gitlab-org/gitlab!63626

Fix minor typo in test descriptions

See merge request gitlab-org/gitlab!63682

Stop using basic auth for GKE cluster creation

See merge request gitlab-org/gitlab!62518

Update auto-deploy-image version in docs and note on backups

See merge request gitlab-org/gitlab!63672

Wait until DB is ready to list data on legacy storage

See merge request gitlab-org/gitlab!63692

Only check for modified paths when the branch is updated

See merge request gitlab-org/gitlab!63523

Add backend sources for inviting members to be recorded

See merge request gitlab-org/gitlab!62732

chore: Drop optimize_sql_query_for_security_report feature flag [RUN ALL RSPEC] [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!63558

Replace work_in_progress with draft

See merge request gitlab-org/gitlab!63473

Replace work_in_progress with draft

Changelog: changed

Add clean_gitlab_redis_shared_state to global_service_spec

See merge request gitlab-org/gitlab!63077

Geo - Successful sync should cause verification

See merge request gitlab-org/gitlab!63104

Added more granular style for roles

See merge request gitlab-org/gitlab!63686

This is needed to support:

1. Verification of mutable types
2. Automatic healing of verification failures

Changelog: changed
EE: true

Merge branch 'cleanup-deployments_finder_implicitly_enforce_ordering_for_updated_at_filter-feature-flag' into 'master'

Clenup deployments_finder_implicitly_enforce_ordering feature flag [RUN ALL RSPEC] [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!63617

Fix timeouts on when informing users of expiring SSH keys

See merge request gitlab-org/gitlab!63623

Add keyset pagination

Changelog: fixed

Enable labels to use reference filter cache

See merge request gitlab-org/gitlab!61648

to reduce SQL queries

Changelog: performance

Remove vue_admin_users feature flag [RUN ALL RSPEC] [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!61129

Changelog: fixed
MR: gitlab.com/gitlab-org/gitlab/-/merge_requests/63523
EE: true

Required to prevent Docker upgrade to 14.0 if there
data on legacy storage.

See: https://gitlab.com/gitlab-org/omnibus-gitlab/-/merge_requests/5311#note_590454698

Changelog: changed

Fix the Cluster Management Proj Template

See merge request gitlab-org/gitlab!63666

Simplify requirements for container-scanning

See merge request gitlab-org/gitlab!63584

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/330261

Add name of the trigger job in title of downstream

See merge request gitlab-org/gitlab!63454