To control the default value by carrier configuration,
- Add a carrier option to control default Enhanced 4G LTE mode enabled.
- Remove initializing Settings.Global.ENHANCED_4G_MODE_ENABLED.
Test: manual - Checked that the "Enhanced 4G LTE mode" can be controlled
by carrier config.
Bug: 67725875
Change-Id: Ic714abcae5c388cc12e6c4b1f45e2abb07febf54