Fix shutdown waitgroup panic (#35676)

This PR fixes a panic issue in the WaitGroup that occurs when Gitea is
shut down using Ctrl+C.
It ensures that all active connection pointers in the server are
properly tracked and forcibly closed when the hammer shutdown is
invoked.
The process remains graceful — the normal shutdown sequence runs before
the hammer is triggered, and existing connections are given a timeout
period to complete gracefully.

This PR also fixes `no logger writer` problem. Now the log close will
only be invoked when the command exit.

- Fixes #35468
- Fixes #35551
- Fixes #35559
- Replace #35578

---------

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

cmd/web.go

@@ -156,7 +156,6 @@ func serveInstall(cmd *cli.Command) error {
 	case <-graceful.GetManager().IsShutdown():
 		<-graceful.GetManager().Done()
 		log.Info("PID: %d Gitea Web Finished", os.Getpid())
-		log.GetManager().Close()
 		return err
 	default:
 	}
@@ -231,7 +230,6 @@ func serveInstalled(c *cli.Command) error {
 	err := listen(webRoutes, true)
 	<-graceful.GetManager().Done()
 	log.Info("PID: %d Gitea Web Finished", os.Getpid())
-	log.GetManager().Close()
 	return err
 }