[lworld] RFR: 8371357: [lworld] Remove EnableValhalla [v2]

[Coleen Phillimore]

On Mon, 15 Dec 2025 16:39:03 GMT, Paul Hübner <phubner at openjdk.org> wrote:

>> Hi all,
>> 
>> This removes the `EnableValhalla` in favour of the `--enable-preview` flag. Concretely:
>> * I've replaced most of the `EnableValhalla` checks with `Arguments::is_valhalla_enabled()`. 
>> * Some checks were redundant and could be removed entirely.
>> * I've made the `EnableValhalla` flag obsolete.
>> * Some tests had to be updated.
>> 
>> This greatly changes the semantics of tests. I've refined some test groups to make it easier.
>> 
>> Testing: tiers 1-4.
>
> Paul Hübner has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Remove wrong comment.
>  - Fix imports.

Marked as reviewed by coleenp (Committer).

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PR Review: https://git.openjdk.org/valhalla/pull/1759#pullrequestreview-3579206047