Do not construct instantiation for checking propagating instantiations spurious ...

Do not construct instantiation for checking propagating instantiations spurious (#7390)

This makes the check for when an instantiation is "propagating" faster by not constructing the substitution + rewriting of the entire formula, and instead threading the substitution through the entailment check utility's evaluateTerm utility.

On a handful of challenge Facebook benchmarks, we go 35 seconds -> 18 seconds with this change.

This also eliminates the argument exp to the evaluateTerm method, which is no longer used, and eliminates hasSubs from several methods, which is redundant.