Add relay snapshot test scenario with low bandwidth on data socket

[frdeso]

This test highlights a race in the relay snapshot mode. This testcase triggers a race where the trace is unreadable because tracing is stopped eventhough data is still in flight.

This PR only provides a testcase/reproducer and does not provide a fix.

This PR also includes some cleanups of the snapshot testcases.

[jgalar]

@PSRCode Are you okay with the first two commits (cleanup)? I could merge those and wait for a fix to merge the new test.

[PSRCode]

@jgalar first two looks good. Go ahead.

@frdeso Still waiting for feedback regarding the commit message of the test.

[frdeso]

I updated the commit message but we will need to update it again when we come up with a fix.