[HACKERS] Make pg_regress print a connstring with sockdir

It's a pain having to find the postmaster command line to get the port pg_regress started a server on. We print the port in the pg_regress output, why not the socket directory / host?

How about

per the attached?

If you'd prefer nicer wording at the expense of two lines, maybe

connection string: 'port=50848 host=/tmp/blah'

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