Fix BF failure introduced by commit
b3f6b14cf4.
The test added by commit
b3f6b14cf4 uses a non-superuser and forgot to set
up pg_hba.conf to allow connections from it. The special setup is only
needed on Windows machines that don't use UNIX sockets.
As per buildfarm
Discussion: https://postgr.es/m/CAJpy0uCfrSspV1x3VWkgamqyhYaUWQZpP0nqjJx4YPvKqN6P_A@mail.gmail.com