[jdk18u] RFR: 8281318: Improve jfr/event/allocation tests reliability [v2]

[Aleksey Shipilev]

On Wed, 16 Mar 2022 17:09:45 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Clean backport to improve JFR tests on x86_32.
>> Needs [JDK-8281638](https://bugs.openjdk.java.net/browse/JDK-8281638) as the follow-up.
>> 
>> Additional testing:
>>  - [x] Linux x86_32 fastdebug, affected tests fail without the patch, pass with it
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into JDK-8281318-jfr-32bit
>  - Backport 65831eb294b6f1f5f99988836c00005d41c27fd3

Got the push approval.

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PR: https://git.openjdk.java.net/jdk18u/pull/42