Fix NullPointerException in group syncing

We were trying to set the scopes too early in the creation of a
GoogleCredential.  They aren't yet known at this point in the code and should be
an empty collection (and also not null, which yields an NPE).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132477868

java/google/registry/request/BUILD

@@ -42,6 +42,7 @@ java_library(
         "//java/com/google/api/client/json",
         "//java/com/google/api/client/json/jackson2",
         "//java/com/google/common/base",
+        "//java/com/google/common/collect",
         "//third_party/java/appengine:appengine-api",
         "//third_party/java/dagger",
         "//java/google/registry/config",