Reland "[cleanup] Move methods to V8_DEPRECATED"

This is a reland of a6e3cdd9

Now only changes ObjectTemplate::NewInstance.

Original change's description:
> [cleanup] Move methods to V8_DEPRECATED
>
> Updates ObjectTemplate::NewInstance and FunctionTemplate::GetFunction
> from V8_DEPRECATED_SOON to V8_DEPRECATED, now that they're unused in
> chrome.
>
> Bug: v8:7294, v8:7295, v8:8238
> Change-Id: Ic7cb2c410ff812f73cfd108551f2a1a20722df07
> Reviewed-on: https://chromium-review.googlesource.com/c/1344151
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#57657}

Bug: v8:7294, v8:7295, v8:8238
Change-Id: I52ec021bc92600f67cf27791d5b2df2a4342a4d5
Reviewed-on: https://chromium-review.googlesource.com/c/1348079Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57760}

include/v8.h

@@ -6045,7 +6045,7 @@ class V8_EXPORT ObjectTemplate : public Template {
                                                  size_t index);
 
   /** Creates a new instance of this template.*/
-  V8_DEPRECATE_SOON("Use maybe version", Local<Object> NewInstance());
+  V8_DEPRECATED("Use maybe version", Local<Object> NewInstance());
   V8_WARN_UNUSED_RESULT MaybeLocal<Object> NewInstance(Local<Context> context);
 
   /**