[starnix] Update zombification test to provide errno on failure

Bug: 476408161
Change-Id: I355839671ea5979c798d6bd942457f9268e0fe3f
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1496598
Fuchsia-Auto-Submit: Wez <wez@google.com>
Reviewed-by: Ambre Williams <ambre@google.com>
Commit-Queue: Wez <wez@google.com>
Reviewed-by: Maria Glukhova <mariagl@google.com>
1 file changed