Load test Syncstorage postgres

[data-sync-user]

Run a load test against the new Syncstorage postgres based environment.

We’ve historically captured load testing results here: https://docs.google.com/document/d/1dY7Jltgw9JvrytTvXjgHYUmzbZbrJyMVb3fBap6L8l8/edit?tab=t.0#heading=h.sdhqkty92i0w

We should consider fixing https://mozilla-hub.atlassian.net/browse/STOR-310 for such load testing. We have +historically used+ what STOR-310 refers to as option #2 for loadtesting, which involves requesting credentials from Tokenserver (which is a more extensive e2e test as it involves both syncstorage and tokenserver)

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