HPCC-11933 Fix WsSMC.setActivityResponse to not update Activity cache

The Activity cache should not be updated in WsSMC.setActivityResponse().
This fix changes the code to not update the Activity cache in WsSMC.
setActivityResponse().

Signed-off-by: wangkx <kevin.wang@lexisnexis.com>
Merge pull request #6248 from richardkchapman/activity_cache_modified_4.2.6

HPCC-11933 Fix WsSMC.setActivityResponse to not update Activity cache

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>