Fix "call to undefined' PHPStan-0 issues in migration system

Closes #3469836

core/modules/migrate/tests/src/Kernel/MigrateTestBase.php

@@ -175,7 +175,7 @@ protected function executeMigration($migration) {
       $this->migration = $migration;
     }
     if ($this instanceof MigrateDumpAlterInterface) {
-      static::migrateDumpAlter($this);
+      $this->migrateDumpAlter($this);
     }
 
     $this->prepareMigration($this->migration);