Help panel: Do not require help desk to be configured

As part of scaling Growth features across multiple wikis,
we want to be able to deploy to wikis with no local help desk.

Soon, we are going to switch to mentorship by default,
but help desk is still going to be used as a fallback. If even
help desk is not around, no ask-help module should be displayed.

Bug: T273118
Change-Id: I6bf58ca26d29a1badc812bd48a6902a4b4cfad92
(cherry picked from commit 686b4a6a97b1e7053f89ba05f3360e63a528a66b)