Ensure mysql rows responses are closed

[timvaillancourt]

Description

This PR ensures the rows-responses from the MySQL driver are closed by using a defer rows.Close(), in order to follow database/sql best practices

Also, these linters are introduced to ensure we don't have this problem again:

1. rowserrcheck

   checks whether Err of rows is checked successfully

2. sqlclosecheck

   Checks that sql.Rows and sql.Stmt are closed

This PR resolves these linter errors:

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.