Fix Null Pointer crash

Fixing null pointer crash in MapClientContent. This happens when the watch
starts the MapClientController and doesn't have a telephony subscription.

aosp/2129638 already fix this but didn't added a test

Bug: 263323082
Bug: 267298837
Test: atest BluetoothInstrumentationTests
Tag: #stability
Change-Id: Icc2f8c49453744e1db36b30954867e79ef361fcf
(cherry picked from commit 1a670ca10b51642fa4a8e3a0e84a5f787a92d676)