HPCC-9662 Rename 'Virtual Memory' column to 'Swap' in Preflight page

It is suggested that the 'Virtual Memory' column should be renamed
as 'Swap' in the Preflight result page.

Signed-off-by: Kevin Wang <kevin.wang@lexisnexis.com>
Merge pull request #4625 from wangkx/h9662

HPCC-9662 Rename 'Virtual Memory' column to 'Swap' in Preflight page

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>