RFR: 8343801: Change string printed by nsk_null_string for null strings

[Leonid Mesnik]

On Tue, 12 Nov 2024 19:59:46 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Trivial change to test comment.  Ran vmTestbase/nsk/jvmti tests locally.

I think it is a trivial. Looks good.

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Marked as reviewed by lmesnik (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22047#pullrequestreview-2430752978