Schema: MySQL cleanup should only touch tables from the SchemaBuilder #126

Part of #102. Line numbers refer to branch chore/php-8.4-dependabot (#98). Verified = reproduced, suspected = from reading the code.

• deleteData() deletes from every table in the database (MysqlBasedSchemaStrategy.php:55-58). Suspected.
  • Views get DELETE FROM view, which errors for non-updatable views. This part can be fixed in 7.x via TABLE_TYPE = 'BASE TABLE'.
  • Tables the SchemaBuilder doesn't own, such as doctrine_migration_versions and messenger_messages, are wiped too. With USE_PRE_INITIALIZED_SCHEMA that destroys migration state.
• listTableNames() (:34) honours DoctrineBundle's schema_filter, so filtered-out tables are not dropped, and their CREATE then fails in a new process. Suspected.

Breaking: tables outside the SchemaBuilder are no longer emptied.