Migrate @Provides methods to @Binds methods where possible.

@Binds is a much more efficient way to delegate one binding to another in that:
  * The @Binds method does not need to be invoked
  * It does not generate an additional Provider implementation
  * An additional Provider does does not need to be instantiated
Future changes to Dagger's component processor will add even further benefits.

More information: []

ATTENTION REVIEWERS: This migration is being done with global approval.  Per-project approval is not required.

Tested:
    TAP train for global presubmit queue
    []
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125980758

java/google/registry/request/Modules.java

@@ -32,6 +32,7 @@ import com.google.appengine.api.urlfetch.URLFetchServiceFactory;
 import com.google.appengine.api.users.UserService;
 import com.google.appengine.api.users.UserServiceFactory;
 
+import dagger.Binds;
 import dagger.Module;
 import dagger.Provides;
 
@@ -138,11 +139,9 @@ public final class Modules {
    * <p>You must also use the {@link AppIdentityCredential} module.
    */
   @Module
-  public static final class UseAppIdentityCredentialForGoogleApisModule {
-    @Provides
-    static HttpRequestInitializer provideHttpRequestInitializer(AppIdentityCredential credential) {
-      return credential;
-    }
+  public abstract static class UseAppIdentityCredentialForGoogleApisModule {
+    @Binds
+    abstract HttpRequestInitializer provideHttpRequestInitializer(AppIdentityCredential credential);
   }
 
   /**