HDRenderPipeline: Revert a change on taaFrameIndex to allow package to work with Postprocess

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Camera/HDCamera.cs

                 isFirstFrame = false;
             }
 
-            taaFrameIndex = taaEnabled ? (uint)postProcessLayer.temporalAntialiasing.sampleIndex : 0;
+            // TEMP: Re-enable this code once we bump the postprocessing package to 0.1.19 (or above)
+            // current package 0.1.8 don't have the .sampleIndex and it fail with template...
+            // taaFrameIndex = taaEnabled ? (uint)postProcessLayer.temporalAntialiasing.sampleIndex : 0;
+            const uint taaFrameCount = 8;
+            taaFrameIndex = taaEnabled ? (uint)Time.renderedFrameCount % taaFrameCount : 0;
+            // END TEMP
             taaFrameRotation = new Vector2(Mathf.Sin(taaFrameIndex * (0.5f * Mathf.PI)),
                                            Mathf.Cos(taaFrameIndex * (0.5f * Mathf.PI)));