Stop unconditionally emitting vertical space before .TS (table start).

Stop unconditionally emitting vertical space before .TS (table start).
Same change as in groff commit 7ec36dc9 Jul 30 2022 gbranden@
For more details, see https://savannah.gnu.org/bugs/index.php?62841

This change makes sense because:
* It improves the formatting of more pages than it degrades.
* Existing manual pages are wildly inconsistent in which behaviour they
expect: apparently few manual page authors understood the old rules.
* It simplifies the rules of how .TS behaves in man(7)
and makes them more similar to how it behaves in mdoc(7).
* It improves flexibility, making it possible for a table to immediately
follow preceding text without a blank line, which some existing pages
want to use, for example XCreateWindow(3).