The load tests used to directly build EPP, but that becomes
problematic for an upcoming CL that refactors a lot of the
EPP flow code. Instead, use the existing tool endpoint
(conveniently, LoadTestAction is already in the tools module).
This required changing the EppToolServlet to get its
xml from a param rather than from the request payload,
since task queues won't allow both a payload and request
params on the same task.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=124351878