Revert "Re-enable throw when notifications posted can't find channel"

This reverts commit ed0a854b0c2bc1a8e9b9c7f28cd87982ef9d129a.
Bug: 36785228
Change-Id: I26a50c2050c50d8223ed5c20793db565ba9356d7

(cherry picked from commit c83713db6a09698a48b4648f2a8a7a8c9c60773e)
1 file changed