pending tear down check all DNs

Currently, upon APM on, we disallow set up new network if a DNC is in the process of tearing down network. However, it should also disallow set up if the other DNC is in progress of tearing down any networks. Therefore, DNC should check for if there is a global attempt of tearding down all networks on the device.

Fix: 330614714
Test: voice call + data browsing + quickly toggle APM
Test: reporter verified fix
Test: atest

Change-Id: I3e282e15197464ffad00078dc83c09fcee0a5514