Auth: Increase SSO config size limit (#112531)

Increase sso_setting.settings column for MySQL from TEXT to MEDIUMTEXT.

pkg/services/sqlstore/migrations/ssosettings/migrations.go

@@ -16,4 +16,7 @@ func AddMigration(mg *migrator.Migrator) {
 	}
 
 	mg.AddMigration("create sso_setting table", migrator.NewAddTableMigration(ssoSettingV1))
+
+	mg.AddMigration("update settings column to MEDIUMTEXT", migrator.NewRawSQLMigration("").
+		Mysql("ALTER TABLE sso_setting MODIFY COLUMN settings MEDIUMTEXT NOT NULL;"))
 }