Statement completion of statement types that are DDL should drop the prepared statement [JDBC586]

[firebird-automations]

Submitted by: @mrotteveel

Currently, Jaybird always prepares statements. For DDL statements it would be better if statement completion drops the prepared statement from the handle to avoid metadata locks being retained for too long.

[firebird-automations]

Commented by: @mrotteveel

This ticket may be the result of an incorrect assumption, so investigate / reproduce the problem before implementing this. The actual observed problem may have been one of a delete statement retaining said lock.