DOCluster never completes deletion when LB is missing

[timoreimann]

When a DOCluster never manages to create an LB, a delete on the cluster never completes because the delete reconciler always expects an LB to be found or otherwise returns early.

Same question as in #218 arises on how to address this problem, with one possible solution to move forward on a missing LB and delete the finalizer so that the DOCluster deletion can complete.

[timoreimann]

The solution proposed here and in #218 seems to have been implemented by CAPA as well as @prksu described in #218 (comment). I'll follow the same pattern here.

/assign timoreimann