Creation of container volume in Cylindervolumebuilder should not depend on presence of inner volume (was ACTS-402)

Original author Julia Hrdinka @jhrdinka

In case there is just one level of volumes belonging to the same hierachy (e.g. {inner neg endcap, inner barrel, inner pos endcap}) without any inner volume present (which happens also when the beam pipe is present, because it is wrapped in the end) only one volume is present. Because the creation of the container volume only happens when certain wrapping conditions are [fulfilled](https://gitlab.cern.ch/acts/acts-core/blob/master/Core/src/Tools/CylinderVolumeBuilder.cpp#L216)  and this wrapping conditions are only set, in case there is an [inner volume to be wrapped ](https://gitlab.cern.ch/acts/acts-core/blob/master/Core/src/Tools/CylinderVolumeBuilder.cpp#L172), only [one volume will be used](https://gitlab.cern.ch/acts/acts-core/blob/master/Core/src/Tools/CylinderVolumeBuilder.cpp#L236).