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

Limiting the size of issuable description and comments to 1_000_000,
which is close to ~1MB of ASCII characters, which represents 99.9% of
all descriptions and comments we have in DB at the moment. This should
help prevent DoS attacks when comments contain refference strings.

Also this change updates regexp matching the namespaces paths by
limiting the namespaces paths to Namespace::NUMBER_OF_ANCESTORS_ALLOWED,
as we allow 20 levels deep groups.

see https://gitlab.com/gitlab-org/gitlab-ce/issues/61974#note_191274234

After measuring the impact of the namespace storage on
https://gitlab.com/gitlab-org/gitlab-ce/issues/64092. It was decided
that it's performant enough. So we can freely remove the feature flag

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/64092

Move it to DiffPositionableNote concern which will be re-used
in EE in DraftNote model.

Make pipeline failure Slack notifications prettier and more informative

Closes #32495

See merge request gitlab-org/gitlab-ce!27683

This commit adds some formatting to the Slack notifications for pipeline
statuses, as well as adds information about the stage and jobs
that failed in the case of pipeline failure.

Using the sed script from
https://gitlab.com/gitlab-org/gitlab-ce/issues/59758

Use title and description fields for issue trackers

Closes #63690

See merge request gitlab-org/gitlab-ce!30096

- Add two new ActiveRecord models:
  - RootNamespaceStoragestatistics will persist root namespace statistics
  - NamespaceAggregationSchedule will save information when a new update
to the namespace statistics needs to be scheduled
- Inject into UpdateProjectStatistics concern a new callback that will
call an async job to insert a new row onto NamespaceAggregationSchedule
table
- When a new row is inserted a new job is scheduled. This job will
update call an specific service to update the statistics and after that
it will delete thee aggregated scheduled row
- The RefresherServices makes heavy use of arel to build composable
queries to update Namespace::RootStorageStatistics attributes.
- Add an extra worker to traverse pending rows on
NAmespace::AggregationSchedule table and schedule a worker for each one
of this rows.
- Add an extra worker to traverse pending rows on
NAmespace::AggregationSchedule table and schedule a worker for each one
of this rows

- instead of using properties
- backward compatibility has to be kept for now