a.t.f.DateFormat behaves consistently with j.t.DateFormat in en, en-US locale

DateUtils.formatSameDayTime() test is also updated, because the javadoc
refers to j.t.DateFormat directly. It makes sense to follow
j.t.DateFormat behavior.

The rest of a.t.f.DateUtils is not updated because it's used for
different purposes, e.g. date/time interval, relative date/time, duration, etc.
'\u202f' NNBS character use is acceptable in this case because
it's unlikely being parsed.

Bug: 266731719
Test: atest FrameworksCoreTests:android.text.format
Test: atest CtsTextTestCases:android.text.format
Change-Id: Ib5c916e2b7a66a5faef7bf214be25db88213d91d