[InstCombineCalls] Optimize call of bitcast even w/ parameter attributes

Before we gave up if a call through bitcast had parameter attributes.
Interestingly, we allowed attributes for the return value already. We
now handle both the same way, namely, we drop the ones that are
incompatible with the new type and keep the rest. This cannot cause
"more UB" than initially present.

Differential Revision: https://reviews.llvm.org/D119967