[Epic] Validate newer external database versions

[dereknola]

Is your feature request related to a problem? Please describe.
Our current list of databases that we validate against are becoming stale:
https://rancher.com/docs/k3s/latest/en/installation/datastore/

• PostgreSQL (certified against versions 10.7 and 11.5)
• MySQL (certified against version 5.7)
• MariaDB (certified against version 10.3.20)
• etcd (certified against version 3.3.15)
  Most of these versions are quite old, and most are set for EOL in 2023.

Describe the solution you'd like
We need to validate K3s against newer versions of these databases:

• MySQL 8.0
• MariaDB 10.6
• PostgreSQL 14.4
• etcd 3.5

Theses newer DBs all EOL in 2026, which expands coverage for a few more years.

[rancher-max]

I have currently validated the following versions using RDS instances:

• MySQL 8.0.28 (used v1.23.9+k3s1)
• PostgreSQL 14.2-R1 (used v1.24.3+k3s1)
• MariaDB 10.6.8 (used v1.22.12+k3s1)

[rancher-max]

Validated external etcd using v3.5.4. As all four DBs from this issue have now been validated, the only remaining step here is to update the doc and then we can close this out. @dereknola since you're working on the new doc migration, do you want to do that as part of your work, or want me to take that up when it's finished?

[dereknola]

I can do it

[dereknola]

Closed as complete! Documentation update is live.