Ensure approval related workers are correctly marked as idempotent

As discussed in #414759 (comment 3099819609), it seems that these workers that subscribe to MergeRequests::ApprovedEvent are marked as idempotent when they don't appear to be. It may have been incorrectly marked as idempotent.

store.subscribe ::MergeRequests::CreateApprovalEventWorker, to: ::MergeRequests::ApprovedEvent
store.subscribe ::MergeRequests::CreateApprovalNoteWorker, to: ::MergeRequests::ApprovedEvent
store.subscribe ::MergeRequests::ResolveTodosAfterApprovalWorker, to: ::MergeRequests::ApprovedEvent
store.subscribe ::MergeRequests::ExecuteApprovalHooksWorker, to: ::MergeRequests::ApprovedEvent

We need to double check if they are indeed idempotent workers. If not, we need to either try to make it idempotent if possible or mark it as non idempotent workers at least.