Revert "Switch TAP tests of pg_rewind to use a role with minimal permissions"

This reverts commit d4e2a84, which added a new user with limited
permissions to run the TAP tests of pg_rewind.  Buildfarm machine
members on Windows jacana and bowerbird have been complaining about
that, the new role not being able to run the rewind because SSPI is not
configured to allow it.

Fixing the test requires passing down directly the new user to
pg_regress with --create-role so as SSPI can work properly.

Reported-by: Andrew Dunstan
Discussion: https://postgr.es/m/3cd43d33-f415-cc41-ade3-7230ab15b2c9@2ndQuadrant.com

src/bin/pg_rewind/t/RewindTest.pm

@@ -144,20 +144,6 @@ sub start_master
 {
 	$node_master->start;
 
-	# Create a custom role which will be used to run pg_rewind.  This
-	# role is used for all the tests, and has minimal permissions enough
-	# to rewind from an online source.
-	$node_master->psql('postgres', "
-		CREATE ROLE rewind_user LOGIN;
-		GRANT EXECUTE ON function pg_catalog.pg_ls_dir(text, boolean, boolean)
-		  TO rewind_user;
-		GRANT EXECUTE ON function pg_catalog.pg_stat_file(text, boolean)
-		  TO rewind_user;
-		GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text)
-		  TO rewind_user;
-		GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, boolean)
-		  TO rewind_user;");
-
 	#### Now run the test-specific parts to initialize the master before setting
 	# up standby
 
@@ -221,9 +207,6 @@ sub run_pg_rewind
 	my $standby_connstr = $node_standby->connstr('postgres');
 	my $tmp_folder      = TestLib::tempdir;
 
-	# Append the rewind-specific role to the connection string.
-	$standby_connstr = "$standby_connstr user=rewind_user";
-
 	# Stop the master and be ready to perform the rewind
 	$node_master->stop;