Fixed incorrect merge service state

The existing logic for merging service state when device is on
IWLAN does not work properly on AP-assisted mode devices. Fixed
by copying the IWLAN preferred flag into IMS service state so
it can get the correct data RAT for AP-assisted mode devices.

Bug: 134706530
Test: WFC manual tests
Merged-In: Ic18934adb870a0114c913855cdb68e0ef33caa79
Change-Id: Ic18934adb870a0114c913855cdb68e0ef33caa79
(cherry picked from commit 5e640ac8)
(cherry picked from commit e089e3945400d69cf2d823b11ee3b52ea1cc3db6)

CRs-fixed: 2524890
Change-Id: Ic18934adb870a0114c913855cdb68e0ef33caa79