RFR: 8369983: Remove expired ZGC flags for JDK 26

[Albert Mingkun Yang]

On Thu, 16 Oct 2025 08:44:04 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

> Hello,
> 
> The ZGenerational flag was obsoleted in JDK 24 as part of removing the non-generational mode of ZGC in JEP 490. The flag was still obsolete in JDK 25, which is a LTS version, so that user's that might specify/try to use it are prompted with a warning. Now that we're past JDK 25, the flag should be expired. Likewise, the ZMarkStackSpaceLimit flag was obsoleted in JDK 25 and can now be expired in JDK 26.
> 
> Since neither of these flags were documented in `java.md` I haven't added them to the "Removed Java Options" section in that file.

Marked as reviewed by ayang (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/27838#pullrequestreview-3344559499