Remove initialStep track building when running LST

[VourMa]

As shown from the circles below, taken from our 24834.704 workflow (on CPU), the initialStep track building by CKF is still run, even though its output is not really used, except for removing clusters from the inner tracker for the highPtTripletStep seeds. However, previous tests had shown that this removal can be done equally well by using the initialStep pixel seeds. Those studies should be redone and the initialStep CKF track building potentially be removed.