RFR: 8365244: Some test control variables are undocumented in doc/testing.md

[Volkan Yazici]

On Thu, 14 Aug 2025 19:38:39 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> Synchronize `make/RunTests.gmk` keyword variables with `doc/testing.{md,html}`.
>
> Marked as reviewed by erikj (Reviewer).

@erikj79, thanks for the review. 🙇

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PR Comment: https://git.openjdk.org/jdk/pull/26789#issuecomment-3191215905