RFR: 8340306: Add border around instructions in PassFailJFrame

[Phil Race]

On Tue, 17 Sep 2024 12:39:20 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> A trivial change which adds border around instruction text. It makes the text easier to read.
> 
> (In some tests, people added leading spaces to each line to make the instructions easier to read; with the added border, there's no need for this trick.)

Marked as reviewed by prr (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/21038#pullrequestreview-2313340695