Make sure pattern closing logic ignores records that were created manually

We have a MergeRequestsClosingIssues model. In the past we have managed records in this table by parsing an MR's description using the closing pattern (e.g. Closes #4).

Now, we want to be able to create these records using the development widget that exists on the work item detail view. So, we need to find a way for these records we create manually are not deleted when we parse an Mr's description. We are adding a new column in order to allow these manually created records to persist even when the target MR description is updated