Enable CentralNotice CrossWiki Hiding

Originally I31425b0f1328d6d6c628cf07eeca6b29174b79ae reverted
by I866838bc2244bca8be521309237bd9a601758fe3 because it was
introducing caching problems in the mobile cluster.

Those problems should've been fixed in change
If6279142ad768959e1d05f4c67941a6f148d68ec so now we're trying
again.

Bug: 16821
Change-Id: If42914f55956751b0eb7a26d9a5aa64dde41521b