Eliminate use of getBaseType (#8764)

Eliminate use of getBaseType (#8764)

For the model, this was used for ensuring that we skipped enumerating the Real constant 1.0 if the Integer constant 1 already existed in the model. Now, these two nodes are disjoint, and due to #8740, the use of getBaseType in this context has no effect since the set of real and integer constants are disjoint.

It was also used in CEGQI in a similar manner, where since equivalence classes of Int and Real terms are disjoint, it is not necessary to search for e.g. Real variables in integer equivalence classes.