RFR: 8346920: Serial: Support allocation in old generation when heap is almost full [v2]

[Guoxiong Li]

On Fri, 24 Jan 2025 11:14:01 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> This PR restores the support for allocation in old-gen when heap is almost full, detected as non-empty young-gen after full gc, which was removed by mistake in [JDK-8333786](https://bugs.openjdk.org/browse/JDK-8333786). With this change, the benchmark attached to the ticket now completes in ~13 GC.
>> 
>> Test: tier1-5
>
> Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Looks good.

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Marked as reviewed by gli (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23270#pullrequestreview-2575662105