Add a transaction to pickTask (#33543) (#33563)

Backport #33543 

In the old `pickTask`, when getting secrets or variables failed, the
task could get stuck in the `running` status (task status is `running`
but the runner did not fetch the task). To fix this issue, these steps
should be in one transaction.

---------

Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

services/actions/init_test.go

@@ -17,9 +17,7 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	unittest.MainTest(m, &unittest.TestOptions{
-		FixtureFiles: []string{"action_runner_token.yml"},
-	})
+	unittest.MainTest(m)
 	os.Exit(m.Run())
 }