Revert "fix: wrong z order of render buffer blitter"

This reverts commit 64aa339.

Author: zccrs

src/server/qtquick/private/wrenderbuffernode.cpp

@@ -524,13 +524,10 @@ class Q_DECL_HIDDEN RhiNode : public WRenderBufferNode {
     }
 
     RenderingFlags flags() const override {
-        // FIXME: shoule we support DepthAwareRendering?
-        // When enable DepthAwareRendering, render buffer node may have a wrong order.
-        // Disable DepthAwareRendering here.
         if (Q_UNLIKELY(!contentNode))
-            return BoundedRectRendering;
+            return BoundedRectRendering | DepthAwareRendering;
 
-        return {};
+        return DepthAwareRendering;
     }
 
     void releaseResources() override {