Fixes#5788
Table queries where source and destination are phantom nodes
on the same one-way segment can fail to find valid routes.
This is due to a bug in the MLD table generation for the
special case where the query can be simplified to a
one-to-many search.
If the destination is before the source on the one-way segment,
it will fail to find a route.
We fix this case by not marking the node as visited at the start,
so that valid paths to this node can be found later in the search.
We also remove redundant initialization for the source
node as the same actions are performed by a search step.
