[master] RFR: 8310214: [Lilliput] Disable compact headers by default [v3]

[Roman Kennke]

On Mon, 19 Jun 2023 06:22:40 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> This would match the PRs that we eventually upstream, and would capture the tests that are failing/misbehaving without compact headers better. This would require enabling `UCOH` for testing explicitly. I took additional care to allow `@flagless` tests with `-XX:+UnlockExperimentalVMOptions -XX:+UseCompactObjectHeaders`.
>> 
>> Additional testing:
>>  - [x] Checked sample `@flagless` tests run with/without `UCOH`
>>  - [x] Linux x86_64 tier1, out of box
>>  - [x] Linux x86_64 tier1, `-XX:+UnlockExperimentalVMOptions -XX:+UseCompactObjectHeaders`
>>  - [x] Linux x86_64 tier1, `-XX:+UnlockExperimentalVMOptions -XX:-UseCompactObjectHeaders`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Revert TestMetaspacePerfCounters to upstream, fixes test

Still looks good!

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Marked as reviewed by rkennke (Lead).

PR Review: https://git.openjdk.org/lilliput/pull/99#pullrequestreview-1485894049