Guard against disabled app when launcing emergency dialer

OEMs can override emergency dialer, and they can be disabled. Telecomm
service should not fail when that happens.

Fixes: 144312317
Test: manual
Change-Id: Ieb554db8506a38b38b01f3e992d140d0f3150978
Merged-In: Ieb554db8506a38b38b01f3e992d140d0f3150978