RFR: 8364954: (bf) CleaningThread should be InnocuousThread [v2]

[Roger Riggs]

On Thu, 7 Aug 2025 15:42:56 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

>> This migrates a `Thread` introduced in [JDK-8344332](https://bugs.openjdk.org/browse/JDK-8344332) to use `InnocuousThread`, similar to the changes in [JDK-8345432](https://bugs.openjdk.org/browse/JDK-8345432) to migrate other uses of `Thread` in `java.nio` to `InnocuousThread`.
>
> Liam Miller-Cushon has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove '= null'

Marked as reviewed by rriggs (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/26665#pullrequestreview-3098523013