The `BuildStagePrepare` is used to echo the hostname of the machine that
is running the job. If this fails we mark it as a BuildFailure which is
not the case, it should be a system failure. If we fail to prepare the
environment it's the Runner fault and not the users fault.

Since the failure is marked as system failure we no longer try to run
the [artifact upload on
failure](https://gitlab.com/gitlab-org/gitlab-runner/-/blob/73ac97aa/common/build.go#L317)
since the job didn't run and there is nothing to upload.

Having this marked as a system failure would make it more clear to the
user that the problem is with the Runner environment since the user
would not see the "No such directory" error from the `cd` we try to
execute on `BuildStageUploadOnFailureArtifacts`.

Add a link to the documentation to make it more simple for them to
understand what might be going on.

reference https://gitlab.com/gitlab-org/gitlab-runner/-/issues/1379