Convert namespace_details.pending_delete to deleted_at

Currently, we use the pending_delete column to mark that the deletion process has started, but the column name pending_delete is confusing and gives an indication that the record is marked for deletion in the future. Instead, it indicates that the background deletion process has started, and we don't need to return such records to the frontend to avoid returning partial data to the frontend, as the background deletion process has already deleted partial data.

See !170774 (comment 2182658405)

Implementation Status:

✅ Added deleted_at timestamp column (!170898 (merged))
✅ Updated code to use the new column (!171267 (merged))
Both MRs have been merged and changes are scheduled for milestone 17.6

Edited Nov 05, 2024 by Abdul Wadood