tests/trustedcoin: remove from CI, disable temporarily

- Don't spin up a CI node for the minor `trustedcoin` test.
- Add the test to `run-tests.sh`, but disable it because it
  occasionally fails.

.cirrus.yml

@@ -27,7 +27,6 @@ task:
           - scenario: default
           - scenario: netns
           - scenario: netnsRegtest
-          - scenario: trustedcoin
       # This script is run as root
       build_script:
         - echo "sandbox = true" >> /etc/nix/nix.conf