Set demoModeEnabled true or false immediately.

After receiving EVENT_SET_SATELLITE_ENABLED_STATE_CHANGED,
demoModeEnabled should be set to true or false instead of setting it
after all radios are turned off. With this change, modem state changes
from PixelSatelliteService will be blocked immediately after satellite
is enabled in demo mode.

Bug: 347791463
Test: b/349192992
Flag: EXEMPT bugfix

Change-Id: Iee712ddd77f60f7d7dad21a43a337080a538ce4c