Ensure database is cleared/Magento reinstalled when TESTS_CLEANUP is enabled

[joshuaswarren]

Description

When TESTS_CLEANUP is set to enabled, the database should be cleared and Magento reinstalled each time the integration tests are run. This is the expected behavior and the documented behavior according to http://devdocs.magento.com/guides/v2.2/test/integration/integration_test_execution.html#the-testscleanup-constant

In this pull request, I've added a check for the TESTS_CLEANUP variable which we use and only restore the database from a previous dump (instead of installing from scratch) if TESTS_CLEANUP is not enabled.

Fixed Issues (if relevant)

1. Integration tests don't reset the database #10025 Integration tests don't reset the database

Manual testing scenarios

1. Follow the steps in http://devdocs.magento.com/guides/v2.2/test/integration/integration_test_execution.html
2. Ensure that TESTS_CLEANUP is enabled
3. Make some manual change to the integration test database
4. Run the integration tests again
5. Ensure that your change you made in step 3 is no longer present in the database.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[okorshenko]

Could you please take a look at Magento\TestFramework\WebApiApplication::install() this method signature must be compatible with Magento\TestFramework\Application::install($cleanup)