Add TODO to filter by tldState in billing pipeline

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=180973229

java/google/registry/beam/sql/billing_events.sql

@@ -54,6 +54,7 @@ FROM (
     FROM
       `%PROJECT_ID%.%DATASTORE_EXPORT_DATA_SET%.%REGISTRY_TABLE%`
     WHERE
+    -- TODO(b/18092292): Add a filter for tldState (not PDT/PREDELEGATION)
       tldType = 'REAL') ) AS BillingEvent
   -- Gather billing ID from registrar table
   -- This is a 'JOIN' as opposed to 'LEFT JOIN' to filter out