Improve actions notifier for workflow_run (#37088) (#37099)

Backport #37088

Changes:

- Make `GetActionWorkflow` only convert the target workflow
- In `getActionWorkflowEntry`, use `branchName` instead of resolving the
default branch name from `commit.GetBranchName()`
- Add `ref` to `workflow_run` notify input to avoid the empty `ref`
warning

modules/actions/github.go

@@ -59,6 +59,10 @@ func IsDefaultBranchWorkflow(triggedEvent webhook_module.HookEventType) bool {
 		// Github "issues" event
 		// https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#issues
 		return true
+	case webhook_module.HookEventWorkflowRun:
+		// GitHub "workflow_run" event
+		// https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#workflow_run
+		return true
 	}
 
 	return false