[ogs] Added log separators for vtkdiff output.
I find it a bit hard to read the vtkdiff output for failed benchmarks. This MR adds separators in the log output. I am open for other (better) separators.
I find it a bit hard to read the vtkdiff output for failed benchmarks. This MR adds separators in the log output. I am open for other (better) separators.