RFR: 8367626: Parallel: Remove ParallelCompactData::summarize_dense_prefix

[Albert Mingkun Yang]

On Mon, 15 Sep 2025 08:22:40 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Remove the unnecessary summary operation on dense-prefix, because the summary operation is only needed for compaction, but dense-prefix doesn't participate in compaction.
> 
> Test: tier1-5

Thanks for review.

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PR Comment: https://git.openjdk.org/jdk/pull/27286#issuecomment-3308665251