8371357: [lworld] Remove EnableValhalla

[Arraying]

Hi all,

This removes the EnableValhalla in favour of the --enable-preview flag. Concretely:

• I've replaced most of the EnableValhalla checks with Arguments::enable_preview().
• Some checks were redundant and could be removed entirely.
• I've made the EnableValhalla flag obsolete.
• I've left an // EnableValhalla legacy comment where the new --enable-preview checks were introduced, in order to have better bookkeeping. This is temporary and should be removed when the obsolete flag is removed.

Note to self before integrating: add ProblemList labels to issues

This greatly changes the semantics of tests

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Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed (1 review required, with at least 1 Committer)

Issue

• JDK-8371357: [lworld] Remove EnableValhalla (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/valhalla.git pull/1759/head:pull/1759
$ git checkout pull/1759

Update a local copy of the PR:
$ git checkout pull/1759
$ git pull https://git.openjdk.org/valhalla.git pull/1759/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 1759

View PR using the GUI difftool:
$ git pr show -t 1759

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/valhalla/pull/1759.diff

[bridgekeeper]

👋 Welcome back phubner! A progress list of the required criteria for merging this PR into lworld will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.