(rds): MariaDB version constants should not include versions that cannot be used to create new instances

### Describe the bug

These include 10.2.x (which is being EOL'd) and 10.5.9.

Current supported versions are documented here: https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MariaDB.Concepts.VersionMgmt.html

### Expected Behavior

Customer expected to not be able to be able to specify versions for which new instances cannot be created.

### Current Behavior

You get an error message during deployment.

### Reproduction Steps

Create a new MariaDB RDS instance with e.g. version 10.5.9

### Possible Solution

Not sure if this can really be improved outside of documentation. If customers have already created an instance with a version that's not on the list, would changing the version in the CDK app re-create the instance? If so, then we need something in the README explaining the situation.

### Additional Information/Context

_No response_

### CDK CLI Version

2.39.0

### Framework Version

2.39.0

### Node.js Version

16.7

### OS

Windows

### Language

Typescript, Python, .NET, Java, Go

### Language Version

_No response_

### Other information

_No response_

Start by locating the MariaDB version constants used when creating Amazon RDS instances, then compare them with the AWS MariaDB version-management documentation linked in the issue. Check the behavior for version 10.5.9 and 10.2.x. Done means new-instance configuration no longer offers versions that AWS rejects, with the existing-instance behavior documented if it remains relevant.

Written by the indexing model from the issue text.