[Error Handling] Better messaging around cross-partition tests that are certain to fail

[andrew-glenn]

Need to handle cross-partition launches better when creds for the additional partitions aren't present; It'll fail, so don't bother launching.

[gattasrikanth]

Sample config to repro:

project:
  name: my-demo
  shorten_stack_name: true
  template: demo.template
  regions:
    - us-east-1
    - us-gov-east-1
    - us-gov-west-1
    - cn-north-1
    - cn-northwest-1
  tests:
   t1:
    parameters:
      EmailAddress: 'demo@demo.com'

Below is the error message when running taskcat:

·[0;30;41m[ERROR  ] : ClientError An error occurred (InvalidToken) when calling the GetBucketLocation operation: The provided token is malformed or otherwise invalid.
--
786 | Traceback (most recent call last):
787 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cli.py", line 46, in main
788 | cli.run()
789 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cli_core.py", line 308, in run
790 | return getattr(command(), subcommand)(**args)
791 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cli_modules/test.py", line 178, in run
792 | test_definition.create_stacks()
793 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cfn/threaded.py", line 63, in create_stacks
794 | fan_out(self._create_stacks_for_test, {"tags": tags}, tests, threads)
795 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cfn/threaded.py", line 22, in fan_out
796 | results = pool.map(func, payload)
797 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 364, in map
798 | return self._map_async(func, iterable, mapstar, chunksize).get()
799 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 768, in get
800 | raise self._value
801 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 125, in worker
802 | result = (True, func(*args, **kwds))
803 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 48, in mapstar
804 | return list(map(*args))
805 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cfn/threaded.py", line 76, in _create_stacks_for_test
806 | stacks = fan_out(Stack.create, partial_kwargs, test.regions, threads)
807 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cfn/threaded.py", line 22, in fan_out
808 | results = pool.map(func, payload)
809 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 364, in map
810 | return self._map_async(func, iterable, mapstar, chunksize).get()
811 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 768, in get
812 | raise self._value
813 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 125, in worker
814 | result = (True, func(*args, **kwds))
815 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/multiprocessing/pool.py", line 48, in mapstar
816 | return list(map(*args))
817 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_cfn/stack.py", line 272, in create
818 | url=s3_url_maker(
819 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/taskcat/_common_utils.py", line 44, in s3_url_maker
820 | response = s3_client.get_bucket_location(Bucket=bucket)
821 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/botocore/client.py", line 357, in _api_call
822 | return self._make_api_call(operation_name, kwargs)
823 | File "/root/.pyenv/versions/3.8.1/lib/python3.8/site-packages/botocore/client.py", line 676, in _make_api_call
824 | raise error_class(parsed_response, operation_name)
825 | botocore.exceptions.ClientError: An error occurred (InvalidToken) when calling the GetBucketLocation operation: The provided token is malformed or otherwise invalid.