Remove the rest of ShaderDebugging.

Without UID checking, it's basically a no-op that disables shader cache
and stores the shader source code (without ever reading it back).

Source/Core/VideoBackends/D3D/PixelShaderCache.h

@@ -42,8 +42,6 @@ private:
   {
     ID3D11PixelShader* shader;
 
-    std::string code;
-
     PSCacheEntry() : shader(nullptr) {}
     void Destroy() { SAFE_RELEASE(shader); }
   };