Limit read bytes instead of ReadAll (#35928) (#35934)

Backport #35928 by wxiaoguang

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

routers/web/repo/wiki.go

@@ -133,7 +133,7 @@ func wikiContentsByEntry(ctx *context.Context, entry *git.TreeEntry) []byte {
 		return nil
 	}
 	defer reader.Close()
-	content, err := io.ReadAll(reader)
+	content, err := util.ReadWithLimit(reader, 5*1024*1024) // 5MB should be enough for a wiki page
 	if err != nil {
 		ctx.ServerError("ReadAll", err)
 		return nil