Fixing CaloExtensionBuilderAlg problems for q220 runs
Previously, CaloExtensionBuilderAlg would fail for runs where the vertex container was unavailable. This patch makes the vertex container optional such that this algorithm can run. The change allows the run q220 to run to completion without stopping at RAWtoESD because of the error and there is no crash. This also allows for the tracks to be extrapolated and cached such that other algorithms down the line can read from the cache and keep the performance increase.