Refactor tests to use default factory data instead of using dummy input

[peterkos]

For example, https://github.com/codeRIT/hackathon-manager/blob/05d50bb2510bde365897f0cc3219e294589bec88/test/helpers/audit_helper_test.rb#L17-L22

should be refactored down to use defaults found in the user factory.

Also, we should refactor all inline JSON in tests to not be on a single line in this PR. They're really hard to read!