[lworld] RFR: [lworld] Enable all flattening by default

[Tobias Hartmann]

Now that the implementation is sufficiently stable, let's enable all flattening by default. At this point, I think the flags are still useful but we might want to remove/merge them later.

Thanks,
Tobias

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Commit messages:
 - [lworld] Enable all flattening by default

Changes: https://git.openjdk.org/valhalla/pull/1480/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1480&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/valhalla/pull/1480.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1480/head:pull/1480

PR: https://git.openjdk.org/valhalla/pull/1480