Test: Test `Create db.table`, `Create Index on db.table`, `Drop db.table` and `Desc db,table`

**Is your feature request related to a problem? Please describe.**

https://github.com/4paradigm/OpenMLDB/issues/977 will support `Create db.table`, `Create Index on db.table`, `Drop db.table` and `Desc db,table`. So we are going to add related tests for the new features once #1173 has been merged.

**Describe the solution you'd like**
A clear and concise description of what you want to happen.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

**Additional context**
Add any other context or screenshots about the feature request here.

The issue references feature #977 and depends on PR #1173 being merged. Look for existing test files for SQL commands like CREATE, DROP, DESC in the test suite. Start by understanding the test framework and the specific syntax for db.table operations. Write tests that verify creating a table with a database prefix, creating an index on it, dropping it, and describing it.

Scritto dal modello di indicizzazione a partire dal testo della issue.