Pipeline function 'googleStorageBuildLogUpload' not working in post block

See https://github.com/jenkinsci/google-storage-plugin/issues/42
Exactly the same issue, just different build step - `googleStorageBuildLogUpload` doesn't upload Jenkins log in post steps.

Looks like the fix is simple, but potentially more than just this mentioned step is affected, since only `ClassicUploadStep` and `GoogleCloudStorageUploader` have mentions of `setForFailedJobs`.

Start with the linked Google Storage plugin issue 42, then inspect googleStorageBuildLogUpload and the mentions of setForFailedJobs in ClassicUploadStep and GoogleCloudStorageUploader. Reproduce the missing Jenkins log upload in a post block and check whether the same behavior affects the other mentioned steps. Done means the relevant post-block upload succeeds, with regression coverage if the repository provides a matching test location.

Written by the indexing model from the issue text.