Revert "MM-27312 Allow uploading 10 files per post (#16235)" (#16908)

This reverts commit 8e2986e5ed.

store/sqlstore/post_store.go

@@ -86,7 +86,7 @@ func newSqlPostStore(sqlStore *SqlStore, metrics einterfaces.MetricsInterface) s
 		table.ColMap("Hashtags").SetMaxSize(1000)
 		table.ColMap("Props").SetMaxSize(8000)
 		table.ColMap("Filenames").SetMaxSize(model.POST_FILENAMES_MAX_RUNES)
-		table.ColMap("FileIds").SetMaxSize(300)
+		table.ColMap("FileIds").SetMaxSize(150)
 	}
 
 	return s

store/sqlstore/upgrade.go

@@ -963,7 +963,6 @@ func upgradeDatabaseToVersion531(sqlStore *SqlStore) {
 func upgradeDatabaseToVersion532(sqlStore *SqlStore) {
 	// if shouldPerformUpgrade(sqlStore, Version5310, Version5320) {
 	// allow 10 files per post
-	sqlStore.AlterColumnTypeIfExists("Posts", "FileIds", "text", "varchar(300)")
 	sqlStore.CreateColumnIfNotExists("ThreadMemberships", "UnreadMentions", "bigint", "bigint", "0")
 	sqlStore.CreateColumnIfNotExistsNoDefault("Channels", "Shared", "tinyint(1)", "boolean")
 	sqlStore.CreateColumnIfNotExistsNoDefault("Reactions", "UpdateAt", "bigint", "bigint")