Revert "ui: Refactor stable ID generation for GPU virtual displays"

This reverts commit 78c90af2224b43467d854e356492527db0f8eb70.

Reason for revert: Causes assert for certain GPU virtual display Ids in VirtualDisplaySurface.cpp (https://paste.googleplex.com/6474098414977024)

Change-Id: I743312bbab4fd9903e069c3ed4710f9d7901be8d
diff --git a/services/surfaceflinger/CompositionEngine/src/Display.cpp b/services/surfaceflinger/CompositionEngine/src/Display.cpp
index 83b1b68..c18be7a 100644
--- a/services/surfaceflinger/CompositionEngine/src/Display.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Display.cpp
@@ -79,7 +79,7 @@
 }
 
 bool Display::isVirtual() const {
-    return mId.isVirtual();
+    return VirtualDisplayId::tryCast(mId).has_value();
 }
 
 std::optional<DisplayId> Display::getDisplayId() const {