[OpenMP] Delete old plugins

[jhuber6]

Summary

It's time to remove the old plugins as the next-gen has already been set
to default in LLVM 16.

[tianshilei1992]

fix typo

[tianshilei1992]

optimize run lines

[tianshilei1992]

fix test line again

[jhuber6]

Where's dynamic_cuda and dynamic_hsa. Also why not replace plugins with nextgen instead of keeping the name.

[tianshilei1992]

In D142820#4088307, @jhuber6 wrote:

Where's dynamic_cuda and dynamic_hsa. Also why not replace plugins with nextgen instead of keeping the name.

Oh right, the two dynamic libraries have to be moved.

[jhuber6]

Also, I don't think the nextgen plugins managed the tests. Does this patch retain that code?

[JonChesterfield]

Shall we wait to see if people using the nextgen report breakages before deleting the current/previous? I don't think the latest branch has actually shipped to anyone yet

[tianshilei1992]

Seems like the schedule is the end of Feb. I'll update the patch properly by then.

[jdoerfert]

Is this ready?

[jhuber6]

I can commandeer tomorrow

[jhuber6]

Hopefully this works.