[clang] [Sema] Simplify Expr::isUnusedResultAWarning for CXXConstructExpr (#153116)
…Expr
Two tests have new warnings because `warn_unused_result` is now
respected for constructor temporaries. These tests were newly added in
#112521 last year. This is good because the new behavior is better than
the old.
@Sirraide and @Mick235711 what do you think about it?