Backport #25746
Fix #25736
Caused by #24048
Right now we only check the activity type for `pull_request` event when
`types` is specified or there are no `types` and filter. If a workflow
only specifies filters but no `types` like this:
```
on:
pull_request:
branches: [main]
```
the workflow will be triggered even if the activity type is not one of
`[opened, reopened, sync]`. We need to check the activity type in this
case.