RFR: 8261: Use test flag to skip JDP multicast tests in JolokiaTest

[Alex Macdonald]

On Wed, 11 Sep 2024 19:40:23 GMT, Martin Skarsaune <duke at openjdk.org> wrote:

> I just became aware that there is a new flag used to skip JDP tests. 
> I previously added some env checking to skip similar multicast tests for Jolokia. 
> Hence it would be a lot cleaner to use the new standardized mechanism for this.
> Trying out whether this fixes [JMC-8261](https://bugs.openjdk.org/browse/JMC-8261)

I took this branch and ran the actions on my own fork, there's a style issue that needs to be fixed by running `mvn spotless:apply`, but the fix for Mac doesn't seem to be working as intended:

https://github.com/aptmac/jmc/actions/runs/11522768181/job/32079324937#step:9:16964

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PR Comment: https://git.openjdk.org/jmc/pull/588#issuecomment-2438440263