activemq: Adding plist again, addressing #39477

[douglasjose]

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activemq: Adding plist configured with AbandonProcessGroup=true, addressing original issue in #39477.

[dunn]

Thanks! Merged as 6cafb22.

[DomT4]

This should have probably been opt_libexec, or we're going to have the same problem where the plist needs unloading, replacing & reloading every revision/update.

[DomT4]

7af943d

[dunn]

Oops, thanks!

[DomT4]

No worries 😃