Replace HashMap with ArrayMap in LocaleUtils

LocaleUtils#filterByLanguage() always perform sort before returning
the result hence enumeration order of HashMap/ArrayMap does not affect
the final result.  Hence we should be able to safely replace HashMap
with ArrayMap.

Also, ArrayMap#valueAt() allows us to copy values into an array
without iterator object.

Bug: 119839847
Test: atest FrameworksServicesTests:com.android.server.inputmethod.LocaleUtilsTest
Change-Id: I898ffcf18110538cbb777e85df21c815e8ed030c