Do some performance optimize for issues list and view issue/pull (#29515) (migration only)

Refs: https://codeberg.org/forgejo/forgejo/pulls/2679#issuecomment-1720941

models/migrations/migrations.go

@@ -568,6 +568,8 @@ var migrations = []Migration{
 	NewMigration("Add default_wiki_branch to repository table", v1_22.AddDefaultWikiBranch),
 	// v290 -> v291
 	NewMigration("Add PayloadVersion to HookTask", v1_22.AddPayloadVersionToHookTaskTable),
+	// v291 -> v292
+	NewMigration("Add Index to attachment.comment_id", v1_22.AddCommentIDIndexofAttachment),
 }
 
 // GetCurrentDBVersion returns the current db version

models/migrations/v1_22/v291.go

@@ -0,0 +1,14 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_22 //nolint
+
+import "xorm.io/xorm"
+
+func AddCommentIDIndexofAttachment(x *xorm.Engine) error {
+	type Attachment struct {
+		CommentID int64 `xorm:"INDEX"`
+	}
+
+	return x.Sync(&Attachment{})
+}