Re: tweak to a few index tests to hits ambuildempty() routine.

a.kozhemyakin@postgrespro.ru writes:
> But my point is that after 4fb5c794e5 for most developer setups and
> buildfarm members, e.g.:
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=guaibasaurus&dt=2022-09-25%2001%3A01%3A13
> https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=tayra&dt=2022-09-24%2020%3A40%3A00
> the ginbulkdelete() most probably is not tested.
> In other words, it seems that we've just lost the effect of 4c51a2d1e4:
> Add a test case that exercises vacuum's deletion of empty GIN
> posting pages.

Yeah.  You can see that the coverage-test animal is not reaching it
anymore:
https://coverage.postgresql.org/src/backend/access/gin/ginvacuum.c.gcov.html

So it seems clear that 4fb5c794e5 made at least some coverage worse
not better.  I think we'd better rejigger it to add some new indexes
not repurpose old ones.

            regards, tom lane