Post acceptance test clean-up

[ciyer]

We support a few different ways to run tests on a PR deployment.

/deploy

Deploys a PR and runs the Selenium acceptance tests, removing and cleaning-up the deployment after the tests run.

/deploy #persist

Deploys a PR and runs the Selenium acceptance tests and the Cypress acceptance tests, leaving the deployment around after the tests runs.

/deploy #persist #notest #cypress

Deploys a PR and runs only the Cypress acceptance tests, leaving the deployment around after the tests runs.

It would be nice to introduce the possibility to run the Cypress acceptance tests with post-run clean-up and tear down, but it would need to be implemented in a way that would not interfere with the post Selenium acceptance test clean up. There are two ways this could be done:

1. Do not run the Selenium acceptance tests on every deployment and move the clean-up logic in that action to the Cypress acceptance test action
2. Support clean-up flexibly, after the Selenium, Cypress, or both acceptance tests run

The first option is very simple to implement, but requires making a decision to move to Cypress as our primary acceptance-test framework. The second involves more effort, but makes sense if we want to continue to support both test frameworks in parallel.