Improve test output of DAST specs

Summary

Improve the DAST E2E test suite's success and failure output by colorizing it and explicitly outputting success and failure messages.

Improvements

Having colorized, explicit success and failure messages will make the test suite more human friendly, and make it easier for developers who are manually running the specs to tell if they succeeded or failed.

Risks

Low: breaking the DAST E2E test suite.

Involved components

https://gitlab.com/gitlab-org/security-products/dast/tree/master/test