MDEV-33526: Create IS.slave_status table as alias for show replica status command

[an3l]

Basing the PR against the correct MariaDB version

• [x] This is a new feature and the PR is based against the latest MariaDB development branch.
• [ ] This is a bug fix and the PR is based against the earliest maintained branch in which the bug can be reproduced.

PR quality check

• [x] I checked the CODING_STANDARDS.md file and my PR conforms to this where appropriate.
• [x] For any trivial modifications to the PR, I am ok with the reviewer making the changes themselves.

[knielsen]

You need to also create INFORMATION_SCHEMA.slave_status. INFORMATION_SCHEMA.replica_status can be an alias for that.

Use "slave" in the internal names in the code to be consistent with the rest of the code.

In the tests, primarily use IS.slave_status when testing functionality, to be consistent with other tests. (There should also be test(s) to specifically test the availability of the IS.replica_status alias).

[bnestere]

Hey Anel!

Andrei mentioned a similar task, MDEV-32172, which aims to extend the performance_schema with related items. We discussed that SHOW SLAVE STATUS has overlap between the ideas of both information_schema (intending to report on metadata), and performance_schema (intending to report on performance statistics). So the information_schema extension should only report on things that are set by CHANGE MASTER TO (and have a name to reflect that scope, and also be consistent with the rest of the tables, e.g. INFORMATION_SCHEMA.replicas); and then anything run-time should be handled by MDEV-32172 in the performance schema.

[LinuxJedi]

Closing this as it has been implemented, as per comment in the Jira.