add skip ci support for pull request title (#29774)

Extends #28075 to support [skip ci] inside PR titles.

Close #29265

(cherry picked from commit 7a90e5954f8515329f20ff0e391130e1ee7b8864)

Conflicts:
	services/actions/notifier_helper.go
	tests/integration/actions_trigger_test.go
	conflicts easily resolved because of
	[TESTS] Convert more tests to CreateDeclarativeRepo
	[ACTIONS] skip superflous pull request synchronized event (#2314)

docs/content/administration/config-cheat-sheet.en-us.md

@@ -1422,7 +1422,7 @@ PROXY_HOSTS = *.github.com
 - `ZOMBIE_TASK_TIMEOUT`: **10m**: Timeout to stop the task which have running status, but haven't been updated for a long time
 - `ENDLESS_TASK_TIMEOUT`: **3h**: Timeout to stop the tasks which have running status and continuous updates, but don't end for a long time
 - `ABANDONED_JOB_TIMEOUT`: **24h**: Timeout to cancel the jobs which have waiting status, but haven't been picked by a runner for a long time
-- `SKIP_WORKFLOW_STRINGS`: **[skip ci],[ci skip],[no ci],[skip actions],[actions skip]**: Strings committers can place inside a commit message to skip executing the corresponding actions workflow
+- `SKIP_WORKFLOW_STRINGS`: **[skip ci],[ci skip],[no ci],[skip actions],[actions skip]**: Strings committers can place inside a commit message or PR title to skip executing the corresponding actions workflow
 
 `DEFAULT_ACTIONS_URL` indicates where the Gitea Actions runners should find the actions with relative path.
 For example, `uses: actions/checkout@v4` means `https://github.com/actions/checkout@v4` since the value of `DEFAULT_ACTIONS_URL` is `github`.