Removal of Jira Cloud DVCS Support
## Description
With Jira Data Center and Server 8.14, Atlassian has introduced an [official GitLab DVCS connector](https://confluence.atlassian.com/adminjiraserver0814/linking-a-gitlab-or-gitlab-self-managed-repository-with-jira-1043893414.html).
Previous to that, we implemented a workaround to use the GitHub Enterprise DVCS connector. We’ve built [an API](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/api/v3/github.rb) that mimics the GitHub enterprise API to make DVCS work for GitLab.
Additionally, and more importantly, Atlassian will end support for using DVCS with Jira Cloud on May 23rd. This issue captures epics/issues related to the effort of removing support here and migrating any impacted users to the Gitlab for Jira app.
Following May 23rd, users should be able to use the following integrations based on the flavors of GitLab and Jira they use:
- Jira Cloud: Users can use the GitLab for Jira app and/or Basic Jira Integration
- Jira Server or Jira Data Center: Users can use the DVCS integration and/or Basic Jira integration
## Key gaps/priorities to be addressed
- https://gitlab.com/groups/gitlab-org/-/epics/7658+
- https://gitlab.com/gitlab-org/gitlab/-/issues/375458+
- https://gitlab.com/gitlab-org/gitlab/-/issues/391432+
- https://gitlab.com/gitlab-org/gitlab/-/issues/389962+
- https://gitlab.com/gitlab-org/gitlab/-/issues/352411+
## Related links
- [Internal sync doc](https://docs.google.com/document/d/1GDoXPD-ZKcbWvyGGa3KwzKklPBwTV6fNA0w8Kslxlz8/edit?usp=sharing)
- [Migration guide](https://docs.gitlab.com/ee/integration/jira/dvcs/#migrate-to-the-gitlab-for-jira-cloud-app)
- [Marketplace Reviews](https://marketplace.atlassian.com/apps/1221011/gitlab-for-jira-cloud?tab=reviews&hosting=cloud)
epic