[Settings] Remove access to getSimOperator() API

Replace getSimOperator() by having SubscriptionInfo
from getAccessibleSubscriptionInfo().

Bug: 144263441
Test: Manual
make RunSettingsRoboTests -j ROBOTEST_FILTER=ApnEditorTest

Change-Id: I25cc9dc0912564b8d6f8b23b53f3eb20a51eea32
5 files changed