[SYNTH-16456] Make server result optional in `Result`

[Drarig29]

What and why?

The source of truth for a result is the batch and not the server result (which we poll with the /poll_results endpoint).

The server result corresponding to a batch result may happen to never be available, and in that case datadog-ci should fall back to the source of truth (the batch) instead of failing.

When such thing happens for a result, a warning log is printed (The information for result {resultId} of test {publicId} was incomplete at the end of the batch.) and the Result.result property will be undefined.

How?

• Make Result.result optional
• Update fixtures and tests

Review checklist

• [x] Feature or bugfix MUST have appropriate tests (unit, integration)

[datadog-datadog-prod-us1[bot]]

Datadog Report

Branch report: corentin.girard/SYNTH-16456/make-server-result-optional Commit report: 3a2b2d8 Test service: datadog-ci-tests

:white_check_mark: 0 Failed, 1636 Passed, 0 Skipped, 1m 54.37s Total duration (1m 35.44s time saved)