test(accounts-controller): improve uuid mocks

[ccharly]

Explanation

Unify the UUID mocking. With this new refactor we longer have to specify each returned values of mockUUID. It also handles the non-registered accounts (in this case, a random UUID will be generated).

References

N/A

Changelog

N/A (those changes only impact tests)

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate
• I've prepared draft pull requests for clients and consumer packages to resolve any breaking changes