[TESTS] Speed up TestEventSourceManagerRun

- `setting.UI.Notification.EventSourceUpdateTime` is by default 10
seconds, which adds an 10 second delay before the test succeeds.
- Lower the interval to reduce it to at most 3 second delay (the code
only send events when they are at least 2 seconds old 🤷).

(cherry picked from commit c0b4a064e9)

tests/test_utils.go

@@ -12,6 +12,7 @@ import (
 	"path"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"code.gitea.io/gitea/models/db"
 	packages_model "code.gitea.io/gitea/models/packages"
@@ -43,6 +44,9 @@ func InitTest(requireGitea bool) {
 		exitf("Environment variable $GITEA_ROOT not set")
 	}
 
+	// Speedup tests that rely on the event source ticker.
+	setting.UI.Notification.EventSourceUpdateTime = time.Second
+
 	setting.IsInTesting = true
 	setting.AppWorkPath = giteaRoot
 	setting.CustomPath = filepath.Join(setting.AppWorkPath, "custom")