Switch Random to SecureRandom

Someone may @Inject a Random at some point in the future where security matters,
so always provide a secure one.

Also, this shouldn't be in ConfigModule (it's not configuration) -- but that can
be changed separately. We might want a larger refactor that has a utils module
or similar to provide extremely generic things like random number generators.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=217602486

java/google/registry/config/RegistryConfig.java

@@ -33,6 +33,7 @@ import java.lang.annotation.Documented;
 import java.lang.annotation.Retention;
 import java.net.URI;
 import java.net.URL;
+import java.security.SecureRandom;
 import java.util.Optional;
 import java.util.Random;
 import java.util.stream.Collectors;
@@ -1267,7 +1268,7 @@ public final class RegistryConfig {
     @Singleton
     @Provides
     public static Random provideRandom() {
-      return new Random();
+      return new SecureRandom();
     }
   }