Merge non-hardware and hardware IME rotation lists

Currently InputMethodSubtypeSwitchingController has two lists used for
switching, one which includes all non-auxiliary IMEs and subtypes, and
one that is only used for hardware keyboard shortcut switching, based on
the value of isSuitableForPhysicalKeyboardLayoutMapping.

However, all the subtypes suitable for physical (hardware) keyboards
are also non-auxiliary. Thus, this leads to more memory usage for
essentialy duplicate entries. Moreover, this also interferes with the
recency update logic: if the user types using a hardware keyboard for
some subtype, this will update the order in the hardware specific list,
without updating the order in the general list, despite the same
subtype being present in both.

To avoid creating both lists, reduce duplication and improve the
behaviour, this change merges the two lists into one.

Flag: EXEMPT cleanup
Bug: 350969542
Bug: 347693610
Test: atest InputMethodSubtypeSwitchingControllerTest
Change-Id: I762e1bfe98deaf1534fd1a209f8face7a12a6a52