When filterConnections_ is called the grid is not load
balanced, yet. Currently that means that grid() will also return the
unbalanced grid and all processes will see the whole global grid.
We will change semantics of the unbalanced grid soon: Only the root
process will see the whole grid and the others will see an empty
partition of it. Hence filtering on this partition will remove all
connections on all wells in the schedule for non-root processes and
produce wrong results.
For non-root process the filtering needs to be done on the load
balanced grid. This is accomplished by this commit.
bc98b20118