Remove Ofy (#1863)

So long, farewell, adios, ciao, sayonara, 再见!

TESTED=deployed to alpha and used `nomulus list_tlds` to confirm that the web app can receive and serve requests.

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util/src/main/java/google/registry/util/PlaceholderEnvironment.java

@@ -1,82 +0,0 @@
-// Copyright 2020 The Nomulus Authors. All Rights Reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package google.registry.util;
-
-import com.google.apphosting.api.ApiProxy.Environment;
-import com.google.common.collect.ImmutableMap;
-import java.util.Map;
-
-/** A placeholder GAE environment class that is used when masquerading a thread as a GAE thread. */
-public final class PlaceholderEnvironment implements Environment {
-
-  private static final PlaceholderEnvironment INSTANCE = new PlaceholderEnvironment();
-
-  public static PlaceholderEnvironment get() {
-    return INSTANCE;
-  }
-
-  private PlaceholderEnvironment() {}
-
-  @Override
-  public String getAppId() {
-    return "PlaceholderAppId";
-  }
-
-  @Override
-  public Map<String, Object> getAttributes() {
-    return ImmutableMap.of();
-  }
-
-  @Override
-  public String getModuleId() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public String getVersionId() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public String getEmail() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public boolean isLoggedIn() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public boolean isAdmin() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public String getAuthDomain() {
-    throw new UnsupportedOperationException();
-  }
-
-  @SuppressWarnings("deprecation")
-  @Override
-  public String getRequestNamespace() {
-    throw new UnsupportedOperationException();
-  }
-
-  @Override
-  public long getRemainingMillis() {
-    throw new UnsupportedOperationException();
-  }
-}