Re-enable failure for globally windowed, unbounded side input usage

Failing pipelines that use globally windowed, unbounded side inputs at construction time inadvertently broke the TestStream tests (BEAM-14499) and re-enabling this behavior requires that testing streaming pipelines has proper support (BEAM-14500) as current passert.Equals() implementation breaks in non-global contexts. Once proper testing support has been implemented, the failure should be re-instated.