Delete all Limited Release Program (LRP) code

We never used it and don't have any plans to use it going forward. All
conceivable parts of its functionality that we might use going forward have
already been subsumed into allocation tokens, which are a simpler way of
handling the same use case that are also standards-compliant.

Also gets rid of the hideous ANCHOR_ prefix on anchor tenant EPP authcodes
that was only ever necessary because of overloading the authcode for
anchor tenant creation. Going forward it'll be based on allocation tokens,
so there's no risk of conflicts.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=209418194

java/google/registry/util/StringGenerator.java

@@ -23,6 +23,8 @@ import java.util.Collection;
 /** String generator. */
 public abstract class StringGenerator {
 
+  public static final int DEFAULT_PASSWORD_LENGTH = 16;
+
   /** A class containing different alphabets used to generate strings. */
   public static class Alphabets {