[Freeflow][test][angeli] No convergence against analytical solution for first time step

The solution does not properly converge for the first time step. The pressure solution is really weird for very small time steps (as the 10^(-12) that is currently used). It becomes less and less weird the larger the first time step is taken. But even for an initial time step of e.g. 10^(-2) the solution is an unsymmetrical version of what it is supposed to be.

It is clear that the solution has the chance to recover for later time steps as the pressure solution at previous time steps does, in contrary to the velocity solution, not play a role for the current solution.

edit: The problem also persists on the new staggered implementation: !2571 (closed)