Delete unused index when deploy sql

OpenMLDB will create a default index if there is no index option in create statement. But this index may not be used in deployment SQL, which will use much memory. So we will delete the unused index when `Deploy` SQL

Look for the code that creates default indexes and the deployment SQL logic. Understand how indexes are tracked and which are considered 'unused' during deployment. The change likely involves modifying the index management logic in the deployment step to clean up unused indexes. Test by creating a table with a default index, deploying a SQL that doesn't use it, and verifying the index is removed without affecting performance.

Written by the indexing model from the issue text.