[upstream_utils] Remove git version from upstream patches (#4351)

This reduces commit noise when other git versions are used. The version
was removed by passing `--no-signature` to `git format-patch` which is
now documented in the readme.

upstream_utils/llvm_patches/0005-Threading-updates.patch

@@ -183,6 +183,3 @@ index a6ae67066ea0..fc798b7ec1b7 100644
  
      if (!Ptr.load(std::memory_order_relaxed)) {
        void *Tmp = Creator();
--- 
-2.20.1.windows.1
-