Don't update the primaryBouncerShow state if delegate is null

If the delegate is null, the primary bouncer can't actually show,
so we shouldn't update the primary bouncer repo states to "showing=true".
Instead, we'll log and exit early.

Test: atest PrimaryBouncerInteractorTest
Test: presubmit
Bug: 303755862
Change-Id: I743e0ec656f1580acb2a8e6a6011fa92d7b8611e