RFR: 8360458: Rename Deferred<> to DeferredStatic<> and improve usage description

[Stefan Karlsson]

On Wed, 25 Jun 2025 00:36:44 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change that renames Deferred<> to DeferredStatic<>, to
> better reflect the intended usage. (This involves renaming the source file.)
> This change also revises the documentation comment for the class to better
> describe the intended usage.
> 
> In addition, there are a number of cleanups:
> 
> (1) The include guard didn't get updated when the name was previously changed
> to Deferred. It's updated here to reflect the new name.
> 
> (2) There were problems with the include block that are fixed here.
> 
> (3) The changes from JDK-8359923 are backed out. They aren't useful with the
> intended usage model.
> 
> (4) A gtest is added to test the class's functionality.
> 
> Testing: mach5 tier1, including new gtest

Marked as reviewed by stefank (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25964#pullrequestreview-2957100542