enable ssl + ssl_verify_server_cert in the internal client too
* fix replication tests to disable master_ssl_verify_server_cert
because accounts are passwordless - except rpl.rpl_ssl1
* fix federated/federatedx/connect to disable SSL_VERIFY_SERVER_CERT
because they cannot configure an ssl connection
* fix spider to disable ssl_verify_server_cert, if configuration
says so, as spider _can_ configure an ssl connection
* memory leak in embedded test-connect
Instrumenting parallel slave worker thread with wsrep replication hooks.
Added mtr test for testing parallel slave support.
The test is based on the test attached in MDEV-6860 jira tracker.