Enable entitlements by default

Entitlements are almost complete. This commit enables them by default,
in preparation for 8.18/9.0.

Author: rjernst

server/src/main/java/org/elasticsearch/bootstrap/Elasticsearch.java

@@ -117,9 +117,9 @@ private static Bootstrap initPhase1() {
         final PrintStream out = getStdout();
         final PrintStream err = getStderr();
         final ServerArgs args;
-        final boolean entitlementsExplicitlyEnabled = Booleans.parseBoolean(System.getProperty("es.entitlements.enabled", "false"));
+        final boolean entitlementsEnabled = Booleans.parseBoolean(System.getProperty("es.entitlements.enabled", "true"));
         // java 24+ only supports entitlements, but it may be enabled on earlier versions explicitly
-        final boolean useEntitlements = RuntimeVersionFeature.isSecurityManagerAvailable() == false || entitlementsExplicitlyEnabled;
+        final boolean useEntitlements = RuntimeVersionFeature.isSecurityManagerAvailable() == false || entitlementsEnabled;
         try {
             initSecurityProperties();