[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/0023-Add-convienence-feature-to-SmallString.patch

@@ -26,6 +26,3 @@ index 85987811f3c4..d3d469d45d15 100644
  
    // Extra operators.
    SmallString &operator=(std::string_view RHS) {
--- 
-2.20.1.windows.1
-