Remove unneeded preSchemaChange and return null if no changes

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

apps/files_external/lib/Migration/Version1016Date20220324154536.php

@@ -31,15 +31,6 @@ use OCP\Migration\SimpleMigrationStep;
 
 class Version1016Date20220324154536 extends SimpleMigrationStep {
 
-	/**
-	 * @param IOutput $output
-	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
-	 * @param array $options
-	 */
-	public function preSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
-		// FIXME do we need to check for 4000+ values?
-	}
-
 	/**
 	 * @param IOutput $output
 	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
@@ -55,8 +46,9 @@ class Version1016Date20220324154536 extends SimpleMigrationStep {
 
 		if ($column->getLength() > 4000) {
 			$column->setLength(4000);
+			return $schema;
 		}
 
-		return $schema;
+		return null;
 	}
 }