Make foundations not ConquestCritical

Foundations were originally made conquest critical in rP20471.
However, it remains rather frustrating that a player can evade defeat by placing an unbuilt, uncommitted foundation. While allies can revive a player with only a foundation, that cannot happen in 1v1, where it is simply undue frustration, and the inconvenience seems greater than the feature.
This thus removes them again from the conquest critical list.

Patch By: nephele

Differential Revision: https://code.wildfiregames.com/D2674