HPCC-10440 - Ensure padded part copies have matching timestamps

When targeting a larger cluster with CLUSTER(<largercluster>)
Empty parts are created for the extra width. Those parts must
have matching timestamps, otherwise backupnode thinks they
mismatch and tried to copy them.

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #5162 from jakesmith/hpcc-10440

HPCC-10440 - Ensure padded part copies have matching timestamps

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>