improve system tests

- log import errors for test modules
- log output only on test failure
- improve docker system test container
- use go 1.19 in docker system tests
- download go dependencies in docker container
- system tests: color failues output
- imrpove test result output
- do not install golangci-lint in system tests

system/t12_api/gpg.py

@@ -23,6 +23,7 @@ class GPGAPITestAddKey(APITest):
     """
     POST /gpg/key
     """
+    requiresGPG2 = True
 
     def check(self):
         with tempfile.NamedTemporaryFile(suffix=".pub") as keyring: