To fix bug, summary is wrong if nr_enabled_bool=false

The carrier config nr_enabled_bool is false, preferred network mode
should hide 5G UI. This bug is that the summary show 5G item when
nr_enabled_bool is false.
Solution: if nr_enabled_bool is false, it checks capability and then
removes 5G capability of network mode.

Bug: 170460943
Test: make RunSettingsRoboTests ROBOTEST_FILTER=\
EnabledNetworkModePreferenceControllerTest   (PASS)
Change-Id: I3f7d41c196569c0cb61e89cfc270b957e2f0add5
(cherry picked from commit 706036e5)