WifiService: Remove usage of NotificationChannel.setBlockableSystem

For non-signature apps, the default behavior is "blockable". So, this
@hide call is redundant.

For non-mainline devices, the network* channels used by wifi are the "common"
networking channels. On AOSP, they are created by
|SystemNotificationChannels| and marked as "blockable". So, unless the
OEM changes the AOSP version of |SystemNotificationChannels|, they will
continue to get the correct behavior.

Bug: 145921908
Test: Compiles
Change-Id: If705203d92a5f9ea850e42cf0e43efb970295927
1 file changed
tree: b5b8010cbb05c8b393d8782d1fa0a980195bb3d8
  1. apex/
  2. service/
  3. PREUPLOAD.cfg