[llvm] [mlir][spirv] Add mlir-spirv-tests CI to run for mlir-spv target tests (PR #152124)

[Igor Wodiany via llvm-commits]

IgWod-IMG wrote:

> Those checks run on powerful self hosted runners (64 threads) and have good build caching. This workflow runs on the free four core Github runners and Github build caching is generally pretty poor. It is going to be a lot slower.

That makes sense, thanks for investigating.

> Enabling auto-merge requires making the check required. Required checks cannot have path dependencies. I also doubt the community is interested in making this check required.

In the hindsight, I agree we probably don't need this check as required, it just took me by surprise, and was quite busy that day, so I wasn’t sure what to do with it :)

https://github.com/llvm/llvm-project/pull/152124