Merge branch '23223-group-deletion-race-condition' into 'master'

Remove race condition while deleting groups

## What does this MR do?

The intended flow during a group deletion is:

```
  Soft-delete group (sync) -> Delete group projects (async) -> Hard-delete group (async)
```

The soft-delete was run in a transaction, which was committed only after
the async job (for hard-deletion) was kicked off. There was a race
condition here - the soft-delete transaction could complete _after_ the
hard delete completed, leaving a soft-deleted record in the database.

This MR removes this race condition. There is no need to run the
soft-delete in a transaction. The soft-delete completes before the async
job is kicked off.

This MR also adds a migration to delete all existing (soft-deleted) groups left in an inconsistent state
due to this bug.

- Closes #23223 
- EE merge request: gitlab-org/gitlab-ee!886

See merge request !7528

1 files changed, 4 insertions, 6 deletions

diff --git a/app/services/destroy_group_service.rb b/app/services/destroy_group_service.rb
index 0081364b8aa..a880952e274 100644
--- a/app/services/destroy_group_service.rb
+++ b/app/services/destroy_group_service.rb
@@ -6,12 +6,10 @@ class DestroyGroupService
   end
 
   def async_execute
-    group.transaction do
-      # Soft delete via paranoia gem
-      group.destroy
-      job_id = GroupDestroyWorker.perform_async(group.id, current_user.id)
-      Rails.logger.info("User #{current_user.id} scheduled a deletion of group ID #{group.id} with job ID #{job_id}")
-    end
+    # Soft delete via paranoia gem
+    group.destroy
+    job_id = GroupDestroyWorker.perform_async(group.id, current_user.id)
+    Rails.logger.info("User #{current_user.id} scheduled a deletion of group ID #{group.id} with job ID #{job_id}")
   end
 
   def execute