rename and document "index.mapping.date.parse_upper_inclusive" setting for date fields

The setting causes the upper bound for a range query/filter to be rounded up,
therefore the name `round_ceil` seems to make more sense.

Also this commit removes the redundant fourth parameter to DateMathParser.parse(..)
which was never used.
was:    parse(String text, long now, boolean roundUp, boolean upperInclusive)
is now: parse(String text, long now, boolean roundCeil)

closes #3914