[24.1] Fix check for anonymous

[jdavcs]

Fixes MultipleResultsFound error

https://sentry.galaxyproject.org/organizations/galaxy/issues/154954/?project=3&query=is%3Aunresolved&referrer=issue-stream&sort=freq&statsPeriod=24h&stream_index=1

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

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[mvdbeek]

That's a good catch, but it's not going to fix https://sentry.galaxyproject.org/organizations/galaxy/issues/154954/?project=3&query=is%3Aunresolved&referrer=issue-stream&sort=freq&statsPeriod=24h&stream_index=1, which is due to a logged in user who does not have a username running a job. So casting the presence of the username field to bool is just not correct if we don't provide a migration to assign usernames.