[DCSI]: Expose kUseDynamicBackingAllocations flag. Move kUseDynamicBackingAllocations from CompoundImageBacking to gpu/config/gpu_finch_features. This allows other classes to utilize this flag for dynamic backing allocations within the shared image system. It also allows rolling out this feature via finch. Bug: 475210055 Change-Id: I2795452b904c3527b566a08258313172a0d9d863 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7630975 Reviewed-by: Vasiliy Telezhnikov <[email protected]> Commit-Queue: Vasiliy Telezhnikov <[email protected]> Auto-Submit: Vikas Soni <[email protected]> Cr-Commit-Position: refs/heads/main@{#1594076} NOKEYCHECK=True GitOrigin-RevId: 7e6a71de9801ef4140d8159d560daa8d05557f68