Fix LTE attach issue due to wrong initial attach profile.

When SIM cards are changed, the attach profile set in modem is
not changed until data is registered. Some times this leads to
permanent LTE attach failure on LTE only networks.
To fix this, de couple set initial attach apn from the setup data call
apn list. Initial attach apn is always queried from 3GPP sim
records as it is applicable only for LTE attach.
DcTracker registers with 3GPP Iccrecords for records loaded event
exclusively for setting initial attach apn.
This makes set initial attach apn operation depend only on sim
records loaded event irrespective of the data registration state.

Change-Id: I4d7b1fe32f7c2ac1b5b0672e7c03bb489d8de596
CRs-Fixed: 936560