alt_mysql_restore_payload.sh (the DirectAdmin native-restore hook that
imports a plugin-origin backup payload into alt-mariadb) had zero
behavioral test coverage - only hook-installation plumbing was tested.
Add a fake mariadb/mariadb-dump client stub (tracking a simple
existing-databases state file) to exercise the real script end-to-end
without a live server, covering: checksum mismatch rejection,
overwrite=deny enforcement against an existing database, and the
happy-path restore. Add a DA_ALT_MYSQL_SETTINGS_FILE override (same
pattern as worker.sh's PLUGIN_DIR) so the script's settings file can be
pointed at a test fixture instead of the real system one.
Also extend da_integration_install_test.sh to check hook-symlink
install/uninstall coverage for database_delete_pre.sh,
database_user_password_change_pre.sh, database_user_create_post.sh,
and database_destroy_user_post.sh, which were previously untested
(only database_create_pre.sh was checked).
Marek Miklewicz