Replace remaining usage of old arithmetic overflow operations

[zhassan-aws]

In https://github.com/model-checking/kani/pull/1426, new methods for arithmetic overflow operations were added that rely on CBMC's new, more efficient operations: add_overflow_result, sub_overflow_result, and mul_overflow_result. There are still a few usages of the old methods, e.g. add_overflow in kani_compiler::codegen_cprover_gotoc::codegen::intrinsic::GotocCtx::codegen_offset. We should switch all the usages to the new methods, and delete the old methods.