Improve online runner check (#35722)

This PR moves "no online runner" warning to the runs list. 

A job's `runs-on` may contain expressions like `runs-on: [self-hosted,
"${{ inputs.chosen-os }}"]` so the value of `runs-on` may be different
in each run. We cannot check it through the workflow file.

<details>
  <summary>Screenshots</summary>

Before:

<img width="960" alt="3d2a91746271d8b1f12c8f7d20eba550"
src="https://github.com/user-attachments/assets/7a972c50-db97-49d2-b12b-c1a439732a11"
/>

After:

<img width="960" alt="image"
src="https://github.com/user-attachments/assets/fc076e0e-bd08-4afe-99b9-c0eb0fd2c7e7"
/>
</details>

This PR also splits `prepareWorkflowDispatchTemplate` function into 2
functions:
- `prepareWorkflowTemplate` get and check all of the workflows
- `prepareWorkflowDispatchTemplate` only prepare workflow dispatch
config for `workflow_dispatch` workflows.

---------

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

models/actions/task.go

@@ -13,7 +13,6 @@ import (
 	auth_model "code.gitea.io/gitea/models/auth"
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/models/unit"
-	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/timeutil"
@@ -245,7 +244,7 @@ func CreateTaskForRunner(ctx context.Context, runner *ActionRunner) (*ActionTask
 	var job *ActionRunJob
 	log.Trace("runner labels: %v", runner.AgentLabels)
 	for _, v := range jobs {
-		if isSubset(runner.AgentLabels, v.RunsOn) {
+		if runner.CanMatchLabels(v.RunsOn) {
 			job = v
 			break
 		}
@@ -475,20 +474,6 @@ func FindOldTasksToExpire(ctx context.Context, olderThan timeutil.TimeStamp, lim
 		Find(&tasks)
 }
 
-func isSubset(set, subset []string) bool {
-	m := make(container.Set[string], len(set))
-	for _, v := range set {
-		m.Add(v)
-	}
-
-	for _, v := range subset {
-		if !m.Contains(v) {
-			return false
-		}
-	}
-	return true
-}
-
 func convertTimestamp(timestamp *timestamppb.Timestamp) timeutil.TimeStamp {
 	if timestamp.GetSeconds() == 0 && timestamp.GetNanos() == 0 {
 		return timeutil.TimeStamp(0)