RFR: 8331771: ZGC: Remove OopMapCacheAlloc_lock ordering workaround

[Erik Österlund]

On Tue, 7 May 2024 09:00:47 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> After [JDK-8331714](https://bugs.openjdk.org/browse/JDK-8331714), we don't need the Generational Z kludge that works around the lock ranking problem with (now gone) `OopMapCacheAlloc_lock`. I also reverted the `DisableIs*Mark` that was added specifically for that kludge in JDK 21. This simplifies further additions of new marks that do not have to replicate `Disable*` code.
> 
> Additional testing:
>  - [ ] Linux x86_64 server fastdebug, `hotspot_gc`

Nice cleanup! Looks good.

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Marked as reviewed by eosterlund (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19114#pullrequestreview-2042542782