Fix service found callback on subtype update

If a service is found without a requested subtype, then updated to have
that subtype, onServiceUpdated would be sent instead of onServiceFound.

Fix this by tracking which services have been found by each listener, as
whether a service is newly found or updated depends on the options (in
this case the subtype filter) of each listener.

Fixes: 317167170
Test: atest
Change-Id: If8dbe04d858082a872c0f068433a3680331c670b