Do not allow NPE if CarrierConfigManager service is null. am: 5cf46dc254

Original change: https://android-review.googlesource.com/c/platform/packages/services/Telecomm/+/3122851

Change-Id: I215273a9286cd8725c9e46bbd28aee06e4d53eff
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>