Testing for MDEV-9573 and extra replication bugfixes

The initial bug MDEV-9573 was about a race condition / deadlock between STOP SLAVE and querying information schema. There is a test case in comments to the bug report; but the area is weak, poorly tested and error-prone, so more testing were required.

The development tree: bb-10.0-monty

Bugfix testing revealed lots of other problems, so the patch has become more complicated, and then even more tests were required.

The general stress test includes (not necessarily all components were a part of every test run):

• one master and one slave, MBR, GTID and non-GTID replication;
• flow on master: multi-thread DML or DML+DDL
• flow on slave: multi-thread mix of

  CHANGE MASTER

  RESET SLAVE [master name]

  STOP SLAVE [master name]

  START SLAVE [master name]

  STOP ALL SLAVES

  FLUSH [BINARY] LOGS

  SHOW [GLOBAL] STATUS

  SHOW STATUS LIKE '%slave%'

  SHOW SLAVE [master name] STATUS

  SHOW ALL SLAVES STATUS

  SET @@default_master_connection=

  SHOW MASTER STATUS

  RESET MASTER

  FLUSH TABLES WITH READ LOCK ; UNLOCK TABLES

• slave server restarts

Later additions to increase the coverage:

SET [GLOBAL|SESSION] gtid_slave_pos = ...

SET [GLOBAL|SESSION] slave_parallel_threads = ...

SET [GLOBAL|SESSION] slave_domain_parallel_threads = ...

SHOW VARIABLES LIKE '%slave%'

SHOW VARIABLES LIKE '%gtid%'

Intermediate problems were reported in a non-conventional fashion (via emails, on IRC).
Here are some.

Reported via gist:
https://gist.github.com/elenst/30334ec2dbbd4bc181a471507bca2fc3
https://gist.github.com/elenst/616ba9127b1d85984f1d6773abbc712d
https://gist.github.com/elenst/e16c2e79fec9390c2a4676e21bb4f44d
https://gist.github.com/elenst/cf0d1562ae59b6d85e98806803e0f054
https://gist.github.com/elenst/32d2f0846828265271416f88521d353f
https://gist.github.com/elenst/6bb33e4487bc1987fe246e6308e5caf4
https://gist.github.com/elenst/271c4338e00cb059df5776a811b689cd
https://gist.github.com/elenst/e101bbafb826eb8b31fe19a830e93cf0
https://gist.github.com/elenst/64227c213f5a3d3c0dbd3efbeef73940
https://gist.github.com/elenst/f4c6e32a1ea53ca123e16410a59fb6c6
https://gist.github.com/elenst/1245ba1f8637937181337bb090b9d479
https://gist.github.com/elenst/f4c6e32a1ea53ca123e16410a59fb6c6
https://gist.github.com/elenst/7d9664a36e88aa010c0aeabecc1c5eb0

Reported by email, added to gist later:
https://gist.github.com/elenst/473ef51b352db5895e353d2748957477
https://gist.github.com/elenst/1e9faf028749b4b29ca06d84154201fd

https://gist.github.com/elenst/3bec270398eabad06d960e30daa33899
https://gist.github.com/elenst/434aefe3db1207874ebecb86a5d16cc7
https://gist.github.com/elenst/cd438e53575ec3a99ed946bc6be512a2
https://gist.github.com/elenst/6bea1969b873cd36a8c3d1e2638acc8a
https://gist.github.com/elenst/14b38cbb09e8b7291fac95844020c25c
https://gist.github.com/elenst/4a6fe321c579372c91e897b2fd2f509e
https://gist.github.com/elenst/58de8487600acdb0bd0baf92df65287c
https://gist.github.com/elenst/f175e41c3b3a98c8291731ce053c5782
https://gist.github.com/elenst/5bedce461e893c871d4c44253c4a2fd9
https://gist.github.com/elenst/22836bb18d907d3585df51615fed6966
https://gist.github.com/elenst/943ba7138a24a90ed6c062faca5e6e3f