net: bridge: multicast: optimize TO_INCLUDE EHT timeouts

This is an optimization specifically for TO_INCLUDE which sends queries
for the older entries and thus lowers the S,G timers to LMQT. If we have
the following situation for a group in either include or exclude mode:
 - host A was interested in srcs X and Y, but is timing out
 - host B sends TO_INCLUDE src Z, the bridge lowers X and Y's timeouts
   to LMQT
 - host B sends BLOCK src Z after LMQT time has passed
 => since host B is the last host we can delete the group, but if we
    still have host A's EHT entries for X and Y (i.e. if they weren't
    lowered to LMQT previously) then we'll have to wait another LMQT
    time before deleting the group, with this optimization we can
    directly remove it regardless of the group mode as there are no more
    interested hosts

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>