After applying a collapsing toolbar in the Settings app, the factory
reset screen is not displayed correctly. This is because
1) the factory reset page should not essentially have a toolbar since it
has different UI layout form other pages.
2) this page was launched previously as a SubSettings so it applied a
wrong theme.
This change is mainly updating the inheritence structure and specifying
the right theme for the factory reset page in order to have a correct
layout.
Bug: 179457252
Test: robotests and visual verified
Change-Id: I91aec65a120d5a288507d89ace7c9298acdca42b
Update language to comply with Android's inclusive language guidance
See https://source.android.com/setup/contribute/respectful-code for reference
Bug: 161896447
Test: robotest & manual
Change-Id: I94969f6903d047b9bc41b1e8c14096c92c460b38
