Remove extraneous DataHandle from IdealStateCreator

The input data handle to MCParticles is redundant because the tool gets passed MCParticle objects. It also had the wrong type, which failed the checks introduced in Moore!686 (merged). For now we keep the MCVertices input handle (even if not using it directly) to make sure the data is in the TES (as is referenced by the MCParticles). See discussion at !2064 (comment 4002147)

Needed for Moore!686 (merged) Goes together with Brunel!1100 (merged)