texture_cache: dedupe region queries with a picked flag

src/graphics/host_gpu/renderer/cache/textureCache.h

@@ -184,7 +184,6 @@ private:
 	uint64_t                                          m_pressure_gc_memory = 1536ull * 1024 * 1024;
 	uint64_t         m_critical_gc_memory     = 3ull * 1024 * 1024 * 1024;
 	uint64_t         m_gc_tick                = 0;
-	mutable uint32_t m_image_query_epoch      = 0;
 	bool             m_readback_linear_images = false;
 	bool             m_readback_tiled_images  = false;