tests: on AWS proper, cloud-id actually starts with aws not ec2

[blackboxsw]

Proposed Commit Message

tests: on AWS proper, cloud-id actually starts with aws not ec2

Other clouds such as aliyun, brightbox, e24cloud and zstack
which have EC2-like metadata services will not return "aws"
from cloud-id.

Example AWS instance data:
  $ cloud-init query --format '{{platform}} {{cloud_id}}'
  ec2 aws

Additional Context

Test Steps

CLOUD_INIT_CLOUD_INIT_SOURCE=ppa:cloud-init-dev/daily CLOUD_INIT_PLATFORM=ec2  tox -e integration-tests  tests/integration_tests/modules/test_combined.py::TestCombined::test_instance_json_ec2

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[holmanb]

LGTM: Tested and checks out.