[mypyc] Emit native_int instead of int64/int32 in IR test output (#10446)
Fixes mypyc/mypyc#776.
This is a super quick workaround. So far the issue mostly (if not completely) occurs
in c_pyssize_t so making this rtype emits native_int would solve the issue. As a result,
the replace_native_int pass in IR test is now removed.