Fix advanced preferences behavior in AllInOneTetherSettings

In AllInOneTetherSettings, advanced preferences should not be hidden
again after user have expanded them.

Bug: 151954343
Test: CodeInspectionTest; AllInOneTetherSettingsTest; manually test oberved advanced preferences won't be hidden.
Change-Id: If2c7d99b7dcac4149f065eca73022a582924c90b
2 files changed