Filter synthetic OneTimes from billing SQL

I intend to configure ExpandRecurringBillingEventsAction in production in the near future, but until I verify that there's a 1:1 match between OneTimes expanded via SQL and OneTimes expanded via MR, filter the MR-synthetic OneTimes from the billing data view SQL.

I confirmed that this is the only script that consumes data from OneTime.

(Note that the best way would be to check for the SYNTHETIC flag, but syntheticCreationTime has a value iff the flag exists, and parsing the flags field is a relative pain in the neck compared to checking for null -- this is temporary.)

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143108200

java/google/registry/tools/sql/billing_data_view.sql

@@ -146,7 +146,10 @@ LEFT JOIN EACH (
       [%SOURCE_DATASET%.Cancellation]
     WHERE
       -- Filter out Registry 1.0 data - TODO(b/20828509): remove this.
-      __key__.namespace = '')
+      __key__.namespace = ''
+        -- TODO(b/27562876): Filter out synthetic OneTime events until we verify
+        -- that expanded OneTime events via MapReduce are correct and complete.
+        AND syntheticCreationTime IS NULL)
   WHERE
     -- Filter out prober data.
     tld IN