[WFCORE-7072] Use new PolicyUtil SPI to set and get the Policy instance.

Author: darranl

elytron/src/main/java/org/wildfly/extension/elytron/PolicyDefinitions.java

@@ -65,6 +65,7 @@
 import org.wildfly.security.authz.jacc.DelegatingPolicyContextHandler;
 import org.wildfly.security.authz.jacc.ElytronPolicyConfigurationFactory;
 import org.wildfly.security.authz.jacc.JaccDelegatingPolicy;
+import org.wildfly.security.authz.jacc.PolicyUtil;
 import org.wildfly.security.manager.WildFlySecurityManager;
 
 /**
@@ -212,7 +213,7 @@ private void setPolicy(Policy policy) {
 
                     private PrivilegedAction<Void> setPolicyAction(Policy policy) {
                         return () -> {
-                            Policy.setPolicy(policy);
+                            PolicyUtil.setPolicy(policy);
                             return null;
                         };
                     }
@@ -226,7 +227,7 @@ private Policy getPolicy() {
                     }
 
                     private PrivilegedAction<Policy> getPolicyAction() {
-                        return Policy::getPolicy;
+                        return PolicyUtil::getPolicy;
                     }
                 };
             }