Disable SecurityManager in tests (elastic#127789)

SecurityManager is already removed in 9.1 and 8.19, but those changes
are too large to backport to 8.18 and 9.0. This commit changes tests
there to not run with security manager to avoid security manager
specific failures even though release versions only runs with entitlements.

closes elastic#127784
closes elastic#127785
closes elastic#127786

Author: rjernst

test/framework/src/main/java/org/elasticsearch/bootstrap/BootstrapForTesting.java

@@ -120,7 +120,7 @@ public class BootstrapForTesting {
         IfConfig.logIfNecessary();
 
         // install security manager if available and requested
-        if (RuntimeVersionFeature.isSecurityManagerAvailable() && systemPropertyAsBoolean("tests.security.manager", true)) {
+        if (RuntimeVersionFeature.isSecurityManagerAvailable() && systemPropertyAsBoolean("tests.security.manager", false)) {
             try {
                 // initialize paths the same exact way as bootstrap
                 Permissions perms = new Permissions();