Merge "Support subscription for CarrierService#onLoadConfig" am: 33acead6f6 am: 8f4f829dee am: 30d5d44234 am: a2a526d3ee

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1901033

Change-Id: I496de5acfe6d890ae00ef47eee710098b31de4ac