Remove MariaDB 10.2 test from release-13.0

[GuptaManan100]

Description

Since MariaDB 10.2 is EOL, its image is unavailable for testing. This PR removes the test for MariaDB 10.2 from release-13.0

Related Issue(s)

Checklist

• "Backport me!" label has been added if this change should be backported
• Tests were added or are not required
• Documentation was added or is not required Website docs are required.

Deployment Notes

[vitess-bot]

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