Add profiling sample for clear sky

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Sky/SkyRenderingContext.cs

             {
                 if (skyContext.skyParametersHash != 0)
                 {
-                    CoreUtils.ClearCubemap(cmd, m_SkyboxCubemapRT, Color.black, true);
-                    if (m_SupportsConvolution)
+                    using (new ProfilingSample(cmd, "Clear Sky Environment Pass"))
-                        CoreUtils.ClearCubemap(cmd, m_SkyboxGGXCubemapRT, Color.black, true);
+                        CoreUtils.ClearCubemap(cmd, m_SkyboxCubemapRT, Color.black, true);
+                        if (m_SupportsConvolution)
+                        {
+                            CoreUtils.ClearCubemap(cmd, m_SkyboxGGXCubemapRT, Color.black, true);
+                        }
                     }
 
                     skyContext.skyParametersHash = 0;