feat(ex/test/conn-case): make default user dynamic from factory

[firestack]

#2874

There are a few tests which assume what user information they're going to get, but #2864 "revealed" that we hardcode the user for ConnCase, but with #2873 we can now generate dynamic users, so this fixes the tests so that we can dynamically create users.

Depends on:

• refactor:test(ex/conn_case): split conn creation into helper function #2864
• feat(ex/test/factory): make user factory dynamic #2873
• fix(ex/test): make tests against user data dynamic #2874

[firestack]

oops 🙃