Remove unused and misused methods from EppResourceUtils and DomainBase.

The methods in DomainBase were the only callers for the methods in
EppResourceUtils, so I first inlined them. Then I realized that there
were no callers for loadReferencedContacts() anywhere. For loadNameservers(),
all but one invocation actually wanted to load the foreign keys, and was
repeating that work, so I replaced it with loadNameserverFullyQualifiedHostNames().
The last invocation, in the Rdap code, was incorrectly assuming this was an async
load when in fact it blocks, so I replaced it with a real async load.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122433897

java/google/registry/whois/DomainWhoisResponse.java

@@ -34,7 +34,6 @@ import google.registry.model.domain.DesignatedContact.Type;
 import google.registry.model.domain.DomainResource;
 import google.registry.model.domain.GracePeriod;
 import google.registry.model.eppcommon.StatusValue;
-import google.registry.model.host.HostResource;
 import google.registry.model.registrar.Registrar;
 import google.registry.model.translators.EnumToAttributeAdapter.EppEnum;
 import google.registry.util.FormattingLogger;
@@ -89,11 +88,11 @@ final class DomainWhoisResponse extends WhoisResponseImpl {
       .emitContact("Billing", getContactReference(Type.BILLING), preferUnicode)
       .emitSet(
           "Name Server",
-          domain.loadNameservers(),
-          new Function<HostResource, String>() {
+          domain.loadNameserverFullyQualifiedHostNames(),
+          new Function<String, String>() {
             @Override
-            public String apply(HostResource host) {
-              return maybeFormatHostname(host.getFullyQualifiedHostName(), preferUnicode);
+            public String apply(String hostName) {
+              return maybeFormatHostname(hostName, preferUnicode);
             }})
       .emitField("DNSSEC", isNullOrEmpty(domain.getDsData()) ? "unsigned" : "signedDelegation")
       .emitLastUpdated(getTimestamp())