mysql_replication: add basic CI tests with MySQL 5.6

[Andersson007]

SUMMARY

mysql_replication: add basic CI tests with MySQL 5.6, master-standby configuration in one container

it's needed for testing hanged PRs, e.g. #56767

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

mysql_replication

[ansibot]

cc @Alexander198961 @Xyon @banyek @bmalynovytch @bmildren @kurtdavis @michaelcoburn @Oneiroi @tolland
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[bmalynovytch]

Good job again @Andersson007 !
LGTM but maybe should you add a test that checks, after the replication is started, that what you did on master is also done on the slave (ie: creating a table in the previously added db)

[Andersson007]

@bmalynovytch , thank you for reviewing and the suggestion!
I think the master log pos on the slave certainly indicates (when we check slave status) that it works correctly. Look at line 79
However i could add this check later, first of all, i'd like to solve related PRs, e.g. #56767, ASAP

[Andersson007]

@bmalynovytch i added the suggested checks :) please look.

[bmalynovytch]

I thought you'd add a SELECT to check the inserted values 🙂

LGTM
shipit

[bmalynovytch]

Btw, I'm wondering if we shouldn't add a little timer before checking replication occurred properly, as the test could be run before replication actually happens, as it is async, or add a small retry loop, to be sure people don't get false negative tests, just because of load on the test / CI env.

[Andersson007]

yep, just in case, added

[Andersson007]

Thank you, guys, for reviewing and merging!