Remove obsolete workaround for XML generation for flaky tests

[fmeum]

Partially reverts f5cf8b0, which is no longer needed now that test actions opt out of async upload.

[fmeum]

How deterministic are testlogs expected to be? I'm wondering whether it would make sense to always opt out if remote execution for this spawn.

[coeuvre]

I think the XML generation spawn was introduced specifically for minimal mode to avoid downloading testlogs. So we should allow it with remote execution.

[fmeum]

Yes, but what about remote caching? It seems pointless to cache the spawn for every possible duration the test can take, but it should definitely be eligible for remote execution.

[coeuvre]

I think the expectation is: if the test is cached, the xml generation should also be cached.

It seems pointless to cache the spawn for every possible duration the test can take

Maybe use the actual test wall time? For cached test, it means the wall time for the uncached run. I am not sure how, though.

[fmeum]

True, that makes sense. I think this is good to go then, I'll think about whether any of this can be improved for better cacheability.