Revert "cppgc: Move forward Trace(T*) deprecation"

This reverts commit 0609bb83.

Reason for revert: Speculative revert for roll fails: https://ci.chromium.org/ui/p/chromium/builders/try/linux_optional_gpu_tests_rel/85744/overview

Original change's description:
> cppgc: Move forward Trace(T*) deprecation
>
> Bug: v8:13089
> Change-Id: I271addd3a80feaa40520ab2768a2380c3d7ab62f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3780821
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#81939}

Bug: v8:13089
Change-Id: Ic9c0389b1b579821f089dddee7e604d81244a108
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3785446
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Auto-Submit: Deepti Gandluri <gdeepti@chromium.org>
Owners-Override: Deepti Gandluri <gdeepti@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#81944}

include/cppgc/visitor.h

@@ -68,7 +68,7 @@ class V8_EXPORT Visitor {
    * \param member Reference retaining an object.
    */
   template <typename T>
-  V8_DEPRECATED("Do not use Trace() with raw pointers.")
+  V8_DEPRECATE_SOON("Do not use Trace() with raw pointers.")
   void Trace(const T* t) {
     TraceImpl(t);
   }