Fix the comments in the epic geometry implementation to reflect EcalBarreScFi orientation

[wdconinc]

Interesting, I wonder what changed and how long the algorithm has been wrong. From your figures I agree that XY is the correct plane to use here. I retract my previous objection. We should also fix the comments in the geometry implementation so we avoid future confusion.

Originally posted by @sly2j in https://github.com/eic/EICrecon/issues/2094#issuecomment-3365768059