migrations: use go:embed instead of gobindata (#19769)

db/assets.go

@@ -0,0 +1,13 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package db
+
+import "embed"
+
+//go:embed migrations
+var assets embed.FS
+
+func Assets() embed.FS {
+	return assets
+}

db/migrations/migrations.go

@@ -1,6 +0,0 @@
-// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
-// See LICENSE.txt for license information.
-
-//go:generate go-bindata -prefix db/migrations --nometadata -pkg migrations ./mysql/... ./postgres/...
-
-package migrations