[lworld] RFR: 8352737: [lworld] Fix TestIntrinsics after VarHandle support cleanup

[Marc Chevalier]

This remove bailout in 8 cases in `test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestIntrinsics.java`. This use a new small type that is tiny enough to be safely flattened in any case.

This change also makes sure that both branches in `test_*` are taken by asserting the value of `UseArrayFlattening`/`UseFieldFlattening`. One can check that there is at least one scenario for each case. Just add `Asserts.assertTrue(false);` if you have a doubt. Since each case run in a separate VM, I couldn't find an easy way to count that across scenarii, each branch is taken at least once.

There are still some bailout since `compareAndSetFlatValue` (and exchange one too) require array flattening. See https://github.com/openjdk/valhalla/pull/1549 & [JDK-8365978](https://bugs.openjdk.org/browse/JDK-8365978).

Thanks,
Marc

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Commit messages:
 - cleanup
 - More
 - Progress

Changes: https://git.openjdk.org/valhalla/pull/1555/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1555&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352737
  Stats: 178 lines in 1 file changed: 84 ins; 0 del; 94 mod
  Patch: https://git.openjdk.org/valhalla/pull/1555.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1555/head:pull/1555

PR: https://git.openjdk.org/valhalla/pull/1555