Apply more consistent style for command options in TAP tests

This commit reshapes the grammar of some commands to apply a more
consistent style across the board, following rules similar to
ce1b0f9da0:
- Elimination of some pointless used-once variables.
- Use of long options, to self-document better the options used.
- Use of fat commas to link option names and their assigned values,
including redirections, so as perltidy can be tricked to put them
together.

Author: Dagfinn Ilmari Mannsåker <ilmari@ilmari.org>
Discussion: https://postgr.es/m/87jz8rzf3h.fsf@wibble.ilmari.org

src/test/perl/PostgreSQL/Test/BackgroundPsql.pm

@@ -108,14 +108,17 @@ sub new
 	if ($interactive)
 	{
 		$run = IPC::Run::start $psql_params,
-		  '<pty<', \$psql->{stdin}, '>pty>', \$psql->{stdout}, '2>',
-		  \$psql->{stderr},
+		  '<pty<' => \$psql->{stdin},
+		  '>pty>' => \$psql->{stdout},
+		  '2>' => \$psql->{stderr},
 		  $psql->{timeout};
 	}
 	else
 	{
 		$run = IPC::Run::start $psql_params,
-		  '<', \$psql->{stdin}, '>', \$psql->{stdout}, '2>', \$psql->{stderr},
+		  '<' => \$psql->{stdin},
+		  '>' => \$psql->{stdout},
+		  '2>' => \$psql->{stderr},
 		  $psql->{timeout};
 	}