Fix syntax error in dogwrap timeout handler and always collect output

[Matt343]

What does this PR do?

This PR addresses a bug in the timeout handling code in the dogwrap script (#537). If the --timeout argument is used and the child process does not exit before the timeout expires, a syntax error was thrown and no event was sent to the Datadog API.

Description of the Change

I fixed the print syntax within the timeout handling, and also ensured that the stdout and stderr of the child process are still collected if the process times out (this was skipped previously).

Alternate Designs

Possible Drawbacks

Verification Process

I added tests for this behavior, using mocks to simulate different subprocess behavior. (I originally tried to actually run a child process in the tests, but the behavior for signal handling in Azure devops seemed different from local. Someone with more experience in this CI environment could probably add more comprehensive testing 😄)

I also ran the dogwrap script from the command line, with various timeout behaviors, to demonstrate that the error was resolved and the event contained the output from the child process.

Additional Notes

Release Notes

Review checklist (to be filled by reviewers)

• Feature or bug fix MUST have appropriate tests (unit, integration, etc...)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have one changelog/ label attached. If applicable it should have the backward-incompatible label attached.
• PR should not have do-not-merge/ label attached.
• If Applicable, issue must have kind/ and severity/ labels attached at least.

[jirikuncar]

/azp run DataDog.datadogpy.integration

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