Use SharedPreferences for assistant mic switch, move tests to inprocess

Use shared preferences instead of settings.secure for the "show
assistant microphone usage" switch. Also moves the assistant user
sensitive tests to be in-process.

Fixes: 162901322
Test: atest AssistantRoleUserSensitiveTest, select the
GooglePermissionController tests

Change-Id: I9ce5c5a1938cf114254e660160d38bdbc541b5e7