handlePreferenceTreeClick() goes after setChecked() however
configuration may have been altered within setChecked().
Follow same design within MobileDataPreferenceController to fix this
issue. A boolean state will be maintained as the condition when warning
dialog is required when click.
Bug: 148491064
Test: m RunSettingsRoboTests -j ROBOTEST_FILTER=RoamingPreferenceControllerTest
Merged-In: I63c4e2149b0e9efa16fd9ee402652c67eb9c5a4d
Change-Id: I2f9998e87b053c8d30af48f977ef58a7fe9ea829
76bd28fe60