Show databases like

[GuptaManan100]

Description

This PR adds the default database names before the filtering step of SHOW DATABASE queries. Also adds tests for the same.

BEFORE

mysql> show databases like '%ys%';
+--------------------+
| Database (%ys%)    |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

AFTER

mysql> show databases like '%ys%';
+-----------------+
| Database (%ys%) |
+-----------------+
| mysql           |
| sys             |
+-----------------+

Related Issue(s)

• Fixes SHOW DATABASES LIKE doesn't filter properly #7910

Checklist

• Should this PR be backported?
• Tests were added or are not required
• Documentation was added or is not required

Impacted Areas in Vitess

Components that this PR will affect:

• Query Serving
• VReplication
• Cluster Management
• Build/CI
• VTAdmin

[deepthi]

Can you add the before and after output into the PR? Either in the description or as a comment.