[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/0024-OS-specific-changes.patch

@@ -41,6 +41,3 @@ index 77c3a37475d0..f70f15f27da4 100644
    abort();
  }
  
--- 
-2.20.1.windows.1
-