Rework JavaSecurityTest #2082

itests/test/src/test/java/org/apache/karaf/itests/JavaSecurityTest.java has been disabled during the upgrade to JDK21.
See discussion #1992 (comment).

We have some issues with the SecurityManager, which has been deprecated for removal in JDK 17, disabled by default in JDK 21, and permanently disabled in JDK 25 (I refer to the LTS versions only).

This ticket about investigating how Apache Felix handles the removal of SecurityManager in recent JDKs and to derive what is needed on Karaf side.