Remove listen requests properly.

https://googleplex-android-review.googlesource.com/#/c/527772/
correctly stopped adding listen requests to the mNetworkForRequestId
sparse array, but when we remove requests, if it's not getting
serviced by a network, we don't remove it from the network.  That
means that when we go to send a notification for that network we have
a request affiliated with the network, but don't have data for the
request and hit this NPE.

If it's not a request, don't do the optimization and remove it only
from the network servicing the request, but instead scan all networks
and remove it from each, if found.

bug:17239054
Change-Id: I49165ed08c224ef20f703469f9ce39df5f21b163