Disable signal strength reporting when threshold is empty am: bb8155c6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/opt/telephony/+/19972249



Change-Id: I6f9208498c0cc63cbb15c06605a8e381a5fdfc2e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>