Regression tests should be refactored as Au and Catch tests

[ywkaras]

That is, the regression tests run with the -R option on the traffic_server command.

There seems to be consensus that these tests are hard to maintain.

Related issues: https://github.com/apache/trafficserver/issues/5048 https://github.com/apache/trafficserver/issues/2637 https://github.com/apache/trafficserver/issues/1587 https://github.com/apache/trafficserver/issues/5049