ConditionalTargetAdjuster more permissive in canChooseTargetAbility than ideal

~~The reworked #12753 includes a complex fix for this, but it's not a clean solution. As a temporary measure to fix the bug of not being allowed to cast spells, 9c52dfa78516ae32b8df6b634bc3425cd3456b0f makes ConditionalTargetAdjuster always satisfy the pre-activation target requirement.~~

~~Currently, it is *less* permissive than ideal, which is a major problem as it means that cards can not be played when they should be able to. An alternative possible fix is at #12842~~

Major problem now fixed, but it's still not perfectly ideal: when only one mode is playable via mana requirements and only the other mode is playable via target requirements, the card will still be highlighted as playable.