[clang] [Offload] Move HIP and CUDA to new driver by default (PR #84420)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> > There are many `--no-offload-new-driver` test changes. They can be pre-committed to make this default flip modify fewer files.
> 
> I think it's much easier to keep these in a single patch, both for writing and with any potential reverting that it may require.

Since llvm is moving rapidly, reverting a commit that modifies many tests is quite risky, since these tests could have been modified by other changes or just cause merge conflicts for others. I assume that the merit of this patch is obvious (a new feature is in development for quite some time, then it matures and replaces the old feature), so adding `--no-offload-new-driver` (to mark "these tests are old, please update them when the new default has been stable for a while") is non-contentious. Pre-committing the test (which is not risky at all) would make this default flip patch much safer to land or revert.

https://github.com/llvm/llvm-project/pull/84420