Re-enable StandaloneKCFTests

The only test case being run (invoke a blocking action and get a result) fails quite frequently when run in a travis-ci environment. It appears we usually hit the 60 second timeout and return a 202 with the activation id instead of the expected result. This is "ok", but the test is not prepared to handle it.

An alternative would be to modify the test to also accept a 202 response and then poll until the result was available, but that
would take significantly more work.

The test was disabled in https://github.com/apache/openwhisk/pull/5140.

Start with StandaloneKCFTests and the change in pull request 5140; reproduce the Travis CI timeout behavior and inspect how the test handles a 202 response with an activation ID. Done means the test is re-enabled and passes reliably when the action exceeds the blocking timeout.

Written by the indexing model from the issue text.