[Wi-Fi] Fix NetworkRequestErrorDialogFragment exception when rotation

When rotating an androidx fragment, it uses default constructor
to instantiate the new fragment instance. Every androidx fragment
should not set private scope to it's default constructor.

Bug: 153824549
Test: make RunSettingsRoboTests ROBOTEST_FILTER=NetworkRequestErrorDialogFragmentTest
Change-Id: Ie1be0e033aa85d37cb4d85193b05beab72d4d8e7