Look for mariadbd process for MariaDB 10.5+

[ian28223]

What does this PR do?

Looks for mariadbd process instead of mysqld for MariaDB 10.5+

Motivation

AGENT-6383

Missing mysql.performance.cpu_time metric for MariaDB 10.5 hosts, though is is working for MariaDB 5.5 hosts.
It appears in version 10.4 the executable name was changed from mysql to mariadb.

Additional Notes

• https://mariadb.com/docs/features/whats-new/whats-new-in-community-server-105/

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #9543 (a033af4) into master (0c5a76b) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

Flag	Coverage Δ
mysql	84.82% <100.00%> (-0.64%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

[hithwen]

Can you add a new tox env for maria 10.5? (I suggest renaming the existing one), we can also remove 5.6 in exchange since it EOLed in February 2021.

py{27,38}-{5.7,8.0,maria-10.2,maria-10.5}

And then in setenv:

setenv =
...
    maria-10.2: MYSQL_VERSION=10.2.27
    maria-10.5: MYSQL_VERSION=10.5.10