MDEV-32559 ensure spider alter table init queries are executed after ddl recovery
If spider was initialised in init_server_components(), i.e. with
--plugin-load-add, then all alter table init queries are to be
executed in the signal_ddl_recovery_done() handlerton callback. Since
this is part of the spider plugin init, we update the callback
signature to return an int, and deinit the plugin when it fails the
callback.
MDEV-32507 Spider: Use $MTR_SUITE_DIR for init-file files
This should fix certain CI builds where the spider suite test files
and the main suite test files do not follow the same relative paths
relations as the mariadb source.
MDEV-32515 Use $MYSQLD_LAST_CMD in spider/bugfix.mdev_30370
$MYSQLD_CMD uses .1 as the defaults-group-suffix, which could cause
the use of the default port (3306) or socket, which will fail in
environment where these defaults are already in use by another server.
Adding an extra --defaults-group-suffix=.1.1 does not help, because
the first flag wins.
So we use $MYSQLD_LAST_CMD instead, which uses the correct suffix.
The extra innodb buffer pool warning is irrelevant to the goal of the
test (running --wsrep-recover with --plug-load-add=ha_spider should
not cause hang)
