Move to using communicate with a timeout for integ tests

[jfuss]

Issue #, if available:

Description of changes:

Checklist:

• Write Design Document (Do I need to write a design document?)
• Write unit tests
• Write/update functional tests
• Write/update integration tests
• make pr passes
• Write documentation

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[sanathkr]

YES!!!!1

[sanathkr]

in the future, we should parallelize this too

[jfuss]

Agreed. I tried to do that in this PR but required some additional changes in the build tests. We need to fix this part of the tests: https://github.com/awslabs/aws-sam-cli/blob/develop/tests/integration/buildcmd/test_build_cmd.py#L72 because we validate the image was deleted. I think we did this to ensure new tests would all start with downloading images and from the same place. While I agree, this actually added mins to the test runs as well. I was going to try and run all other integ tests but build but wanted to try and keep things scoped and not solve everything at once here.

[jfuss]

Correction: That method verifies we are deleting the container not the image.