Fix new test with comma in build directory.

Fix new test with comma in build directory.

Quote pg_hosts.conf fields derived from the build directory, since
hba.c:next_token() treats a comma as a token separator.  Commit
4f433025f666fa4a6209f0e847715767fb1c7ace introduced pg_hosts.conf and
this test.  A build directory name containing a comma worked before that
commit.  A build directory name containing a quote character has not
worked, so don't handle that.

Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/20260426213252.7a@rfd.leadboat.com