[clang][RISCV][NFC][test] Move riscv-abi.cpp and riscv{32,64}-*abi.c tests to...

[clang][RISCV][NFC][test] Move riscv-abi.cpp and riscv{32,64}-*abi.c tests to use update_cc_test_checks.py

This patch implements an initial step towards refactoring our ABI tests
(moving them to update_cc_test_checks.py). Future patches combine them.

Differential Revision: https://reviews.llvm.org/D134050