MM Renderer - Fix image planes not rendering behind hold out objects.

When an object has useBackground shader on it (or it's a "hold out"
object), the Maya native imagePlane nodes were not rendering in the hold
out, only mmImagePlane was working. This is now fixed.

src/mmSolver/render/RenderOverride.cpp

@@ -130,7 +130,6 @@ RenderOverride::RenderOverride(const MString &name)
     m_sceneOp->setEnabled(true);
     m_sceneOp->setBackgroundStyle(BackgroundStyle::kTransparentBlack);
     m_sceneOp->setClearMask(CLEAR_MASK_DEPTH);
-    m_sceneOp->setExcludeTypes(MHWRender::MFrameContext::kExcludeImagePlane);
     m_sceneOp->setSceneFilter(
         static_cast<MHWRender::MSceneRender::MSceneFilterOption>(
             MHWRender::MSceneRender::kRenderShadedItems));