Clean up remaining AccessController warnings in test library

serviceability/sa/CDSJMapClstats.java gives warnings about the deprecated security manager. Can these test packages be rewritten to not use the security manager?

test/lib/jdk/test/lib/process/ProcessTools.java:450: warning: [removal] AccessController in java.security has been deprecated and marked for removal
                AccessController.doPrivileged((PrivilegedExceptionAction<Void>) () -> {
...
Also:
test/lib/jdk/test/lib/SA/SATestUtils.java
test/lib/jdk/test/lib/NetworkConfiguration.java