Marks paths that do not have any route targets of interest
        for withdrawal.

        Since global tables can have paths with route targets that are not
        interesting any more, we have to clean these paths so that appropriate
        withdraw are sent out to NC and other peers. Interesting route targets
        change as VRF are modified or some filter is that specify what route
        targets are allowed are updated. This clean up should only be done when
        a route target is no longer considered interesting and some paths with
        that route target was installing in any of the global table.

def _clean_global_uninteresting_paths(self):
        """Marks paths that do not have any route targets of interest
        for withdrawal.

        Since global tables can have paths with route targets that are not
        interesting any more, we have to clean these paths so that appropriate
        withdraw are sent out to NC and other peers. Interesting route targets
        change as VRF are modified or some filter is that specify what route
        targets are allowed are updated. This clean up should only be done when
        a route target is no longer considered interesting and some paths with
        that route target was installing in any of the global table.
        """
        uninteresting_dest_count = 0
        interested_rts = self._rt_mgr.global_interested_rts
        LOG.debug('Cleaning uninteresting paths. Global interested RTs %s',
                  interested_rts)
        for route_family in [RF_IPv4_VPN, RF_IPv6_VPN, RF_RTC_UC]:
            # TODO(PH): We currently do not install RT_NLRI paths based on
            # extended path attributes (RT)
            if route_family == RF_RTC_UC:
                continue
            table = self.get_global_table_by_route_family(route_family)
            uninteresting_dest_count += \
                table.clean_uninteresting_paths(interested_rts)

        LOG.debug('Found %s number of destinations had uninteresting paths.',
                  uninteresting_dest_count)