Deadlocking fix for LowEnergyBlock preconditioner for the velocity system

• Problem: For specific type of meshes where the spanwise thickness is 100 times lower than the streamwise length, or height of the computational domain, when LowEnergyBlock is used as a preconditioner for the velocity (u, v, w), it was leading to a deadlock upon execution in parallel in the first iteration.
• Cause: Single element in the spanwise direction & Zero Dirichlet boundaries in both ends of the single element
• Solution: Removed if-statement that checks for non-Dirichlet vertices, hence its commands will be executed for every kind of vertex, Dirichlet, or non-Dirichlet.