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/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index d69bfaf..4b5a68c 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -316,7 +316,7 @@
 
 status_t VirtualDisplaySurface::dequeueBuffer(Source source,
         PixelFormat format, uint64_t usage, int* sslot, sp<Fence>* fence) {
-    LOG_ALWAYS_FATAL_IF(mDisplayId.isVirtual());
+    LOG_ALWAYS_FATAL_IF(GpuVirtualDisplayId::tryCast(mDisplayId).has_value());
 
     status_t result =
             mSource[source]->dequeueBuffer(sslot, fence, mSinkBufferWidth, mSinkBufferHeight,
@@ -616,7 +616,7 @@
 }
 
 status_t VirtualDisplaySurface::refreshOutputBuffer() {
-    LOG_ALWAYS_FATAL_IF(mDisplayId.isVirtual());
+    LOG_ALWAYS_FATAL_IF(GpuVirtualDisplayId::tryCast(mDisplayId).has_value());
 
     if (mOutputProducerSlot >= 0) {
         mSource[SOURCE_SINK]->cancelBuffer(