DEV-42 - Drop database tables when running load-db.

[raylwalters]

This work drops the database tables when running drupal-load-db.

Testing Instructions

1. In a project checkout this branch for the-build "palantirnet/the-build": "dev-dev-42-drupal-load-db"
2. composer up palantirnet/the-build
3. SSH into ddev ddev ssh
4. Run phing load and verify that drupal-load-db runs drush sql-drop -y

[raylwalters]

I believe this is failing code review because of Can't find the custom report class: defaults/standard/phpmd.xml which might be related to https://palantir.atlassian.net/browse/DEV-30?

[raylwalters]

This is now passing code review after pinning phpmd to 2.13.

[jaymejohnson]

lgtm!