RFR: 8330704: Clean up non-standard use of /** comments in some langtools tests

[Iris Clark]

On Mon, 22 Apr 2024 18:02:39 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

> Please review a simple change to clean up inappropriate use of `/**` comments in test code -- most notably to enclose the `jtreg` test description.
> 
> There is no change to the functionality of any test, and (obviously) all tests continue to pass.

Marked as reviewed by iris (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/18896#pullrequestreview-2015514289