TrackVertexAssociationTool+JetAlgorithm: Track decoration fixes.

In TrackVertexAssociationTool, the ReadDecorHandleKey's need to be declared in order for dependencies to be propagated.

There is also no need to have a separate name property.

In the JetAlgorithm configuration, don't add a track decoration tool if it's already done by a separate algorithm.

Actually, decoration should probably always be scheduled as a separate algorithm, which the jet configuration can request. That may work better though with the new job configuration, so won't try to implement that at this point.

See ATLASRECTS-6055 / ATLASRECTS-6057.