RFR: 8361950: Update to use jtreg 8

[Christian Stein]

On Fri, 11 Jul 2025 09:05:40 GMT, Christian Stein <cstein at openjdk.org> wrote:

> Please review the change to update to using jtreg 8.
> 
> The primary change is to the `jib-profiles.js` file, which specifies the version of jtreg to use, for those systems that rely on this file. In addition, the requiredVersion has been updated in the various `TEST.ROOT` files.

I updated both tests to be agnostic about the location to where `jtreg` puts library classes into. See also: https://openjdk.org/jtreg/faq.html#how-do-i-find-the-path-for-the-testng-or-junit-jar-files

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PR Comment: https://git.openjdk.org/jdk/pull/26261#issuecomment-3174373256