Refactor authInfo validation

1) Don't do ofy().load() inside a model class (in DomainAuthInfo)
2) Move the one use of verify into the one caller in ResourceFlowUtils
3) Hosts don't support authInfo, so remove useless code

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=137984809

java/google/registry/model/eppcommon/AuthInfo.java

@@ -15,7 +15,6 @@
 package google.registry.model.eppcommon;
 
 import com.googlecode.objectify.annotation.Embed;
-import google.registry.model.EppResource;
 import google.registry.model.ImmutableObject;
 import javax.xml.bind.annotation.XmlAttribute;
 import javax.xml.bind.annotation.XmlTransient;
@@ -33,13 +32,6 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 @XmlTransient
 public abstract class AuthInfo extends ImmutableObject {
 
-  /**
-   * Verify that the authorization info is valid for the given resource in the given tld.
-   *
-   * @throws BadAuthInfoException if this authorization info is invalid for this resource
-   */
-  public abstract void verifyAuthorizedFor(EppResource eppResource) throws BadAuthInfoException;
-
   protected PasswordAuth pw;
 
   public PasswordAuth getPw() {
@@ -77,12 +69,4 @@ public abstract class AuthInfo extends ImmutableObject {
       return create(value, null);
     }
   }
-
-  /** Returns the repoId for the contact this auth info is associated with. */
-  protected String getRepoId() {
-    return pw.getRepoId();
-  }
-
-  /** Exception to throw when an auth info can't be verified. */
-  public static class BadAuthInfoException extends Exception {}
 }