Move zmq test skipping logic into individual test case.

Summary:
This commit uses the new skip test funcationality added in
232b6665bc3e5b134821dc7584968fb439fd5f44 to skip the zmq tests if the
python zmq module is not available or if bitcoind has been built without
zmq support.

This removes the zmq-specific logic from test_runner.py. In general it's
better if test_runner.py has no knowledge of special cases for
individual tests and is a general purpose test runner.

Backport core's PR10097 and PR10307

Test Plan:

./test/functional/test_runner.py zmq_test.py

Reviewers: schancel, #bitcoin_abc

Reviewed By: schancel, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D955