test: Change ExecuteQueryIT to use ephemeral table/bundle and prefix generator

[trollyxia]

1. Creates an ephemeral table for the tests instead of using the static testEnvRule.env().getTableId().
2. Uses PrefixGenerator for generating tableId and schemaBundleId instead of UUID.randomUUID().
3. Adds @AfterClass teardown to delete the ephemeral table and schema bundle after tests are run.
4. Removes individual test cleanup of schema bundles, as this is now handled in @AfterClass.