MDEV-34053 mariadbbackup privilege REPLICA MONITOR issue

[grooverdan]

• The Jira issue number for this PR is: MDEV-34053

Description

MariaDB-backup needs to check for SLAVE MONITOR as that is what is returned by SHOW GRANTS.

Update test to ensure that warnings about missing privileges do not occur when the backup is successful.

Thanks Eugene for reporting the issue.

Release Notes

Remove erroneous MariaDB-Backup warnings about required privileges

How can this PR be tested?

TODO: modify the automated test suite to verify that the PR causes MariaDB to behave as intended.
Consult the documentation on "Writing good test cases".

If the changes are not amenable to automated testing, please explain why not and carefully describe how to test manually.

Basing the PR against the correct MariaDB version

• 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

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

[LinuxJedi]

I'm not happy that we need this fix at all. But, looks good to me :)