Choice to cast for alternate cost not properly cleaned up if canceled

Steps to reproduce:

1. Begin to cast e.g. [[Foil]] for its alternate cost
2. Cancel the cast
3. Cast it for its standard cost
4. Game log indicates that it was cast for its alternate cost

Probably just cosmetic but potentially indicative of deeper problems

Start by reproducing the canceled alternate-cost cast sequence with a card such as Foil and inspect the cast state used by the game log. Trace where the alternate-cost choice is retained after cancellation; done means a later standard-cost cast is logged as standard cost, with no stale alternate-cost state.

Written by the indexing model from the issue text.