Datastore Backup to BigQuery matches wrong backup name

[ronoaldo]

The query filter used to find the backup that starts with the calculated name currently will find any backup that starts with the name greather than the prefix informed in the configuration.

If there is a "production_backup", previously run by the user, and the backup prefix of the configuratoin is "bigquery", the information from "production_backup" will be used.

A potential solution is to include the line in BuiltinDatastoreToBigqueryIngesterTask.java:

q.addFilter(new FilterPredicate("name",
    FilterOperator.LESS_THAN, backupName + Character.MAX_VALUE));

This will properly perform a "starts with" query on AppEngine.