Job.cancel() makes Job.getResult() unstable, remove it #2339

[basilevs]

Job.cancel() is not synchronized with job's state, so cancelling a running job produces an undefined getResult().
Avoid job.cancel() when getResult() is needed.

Fixes #2339

[github-actions]

Test Results

 1 953 files  ±0   1 953 suites  ±0   1h 23m 44s ⏱️ - 13m 39s
 4 745 tests ±0   4 721 ✅ ±0   24 💤 ±0  0 ❌ ±0 
14 235 runs  ±0  14 053 ✅ ±0  182 💤 ±0  0 ❌ ±0 

Results for commit 8a72997. ± Comparison against base commit 53950e7.

[HeikoKlare]

Thank you for taking a look into this so quickly, @basilevs!
The proposal looks sound to me. Let's give it a try.

[basilevs]

Thank you for taking a look into this so quickly, @basilevs! The proposal looks sound to me. Let's give it a try.

The whole test looks like a big Job framework workaround. I should've followed @jukzi advice and used a filesystem mock.