💥[breaking] Remove cloud files

[yuandrew]

What changed? Removed all cloud files, now that they live at https://github.com/temporalio/cloud-sdk-go

Why? Cloud files have been moved to their own repo, no need to keep them here anymore.

The Go SDK's has not used cloud protos for a few releases now, so this should be safe.

https://github.com/temporalio/sdk-go/issues/1921

How did you test it?

Potential risks