fix(git): avoid unnecessary timers during language stats (#39531)

Replace time.After with a stoppable time.Timer in BatchChecker.CheckPath.
Avoid accumulating up to 6 pending 5-second timers per file on the normal path.
Preserve the existing per-attribute timeout behavior.

---------

Signed-off-by: Calvin Tjoaquinn <calvintjoa23@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/git/attribute/batch.go

@@ -13,6 +13,7 @@ import (
 	"gitea.dev/modules/git"
 	"gitea.dev/modules/git/gitcmd"
 	"gitea.dev/modules/log"
+	"gitea.dev/modules/setting"
 )
 
 // BatchChecker provides a reader for check-attribute content that can be long running
@@ -120,12 +121,17 @@ func (c *BatchChecker) CheckPath(path string) (rs *Attributes, err error) {
 		return fmt.Errorf("CheckPath timeout: %s", debugMsg)
 	}
 
+	timeout := time.NewTimer(5 * time.Second)
+	defer timeout.Stop()
+
 	rs = NewAttributes()
 	for i := 0; i < c.attributesNum; i++ {
 		select {
-		case <-time.After(5 * time.Second):
+		case <-timeout.C:
 			// there is no "hang" problem now. This code is just used to catch other potential problems.
-			return nil, reportTimeout()
+			err = reportTimeout()
+			setting.PanicInDevOrTesting("Unexpected timeout, need to investigate: %v", err)
+			return nil, err
 		case attr, ok := <-c.stdOut.ReadAttribute():
 			if !ok {
 				return nil, c.ctx.Err()