HPCC-12625 subscription notifying erroneously on some changes

If there were >1 subscriber on a parent node, and 1 of the
subscribers was a subscriber with a change below it, but
unrelated to another child subscriber, both were were being
notified, e.g.
/a/b (sub=true)
/a/b/c (sub=false)

change to /a/b/d

/a/b AND /a/b/c were being notified.

Signed-off-by: Jake Smith <jake.smith@lexisnexis.com>
Merge pull request #6670 from jakesmith/hpcc-12625

HPCC-12625 subscription notifying erroneously on some changes

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>