[1d3d][avg] Skip point source if the circle stencil is empty (zero coupling term)

In this case the integration element is zero anyways and there is no coupling  but the pressure may
become NaN and makes the simulation crash due to NaN residuals.
5 jobs for !2923 with fix/1d3d-coupl-average-empty-circle-stencil
latest detached
Status Name Job ID Coverage
  Trigger
passed full-dune-latest-release-clang

passed full-dune-latest-release-gcc

failed full-dune-master-gcc

passed minimal-dune-latest-release-gcc

 
  Downstream Modules
skipped trigger lecture