Despite the comment, DomainAllocateFlow is absolutely registered in
FlowPicker. It gets picked if there's a domain create epp command that
also specifies the allocate extension. Remove the explicit setting of
flowClass, and remove two tests that now fail because DomainCreateFlow
gets loaded - which is the desired behavior.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=125339191