Change pg_dump default for statistics export.

Change pg_dump default for statistics export.

Set the default behavior of pg_dump and pg_dumpall to be
--no-statistics.

Leave the default for pg_restore and pg_upgrade to be
--with-statistics.

Discussion: https://postgr.es/m/CA+TgmoZ9=RnWcCOZiKYYjZs_AW1P4QXCw--h4dOLLHuf1Omung@mail.gmail.com
Reviewed-by: Greg Sabino Mullane <[email protected]>
Reviewed-by: Nathan Bossart <[email protected]>
Reviewed-by: Robert Haas <[email protected]>
Reviewed-by: Tom Lane <[email protected]>