[#68702] Project user filter also includes groups and placeholder users

[EinLama]

Ticket

https://community.openproject.org/wp/68702

What are you trying to accomplish?

Remove the type = User restriction on the filter component, so that groups and placeholder users can also be found.

Included some minor drive-by rubocop fixes for neighboring specs.

Screenshots

What approach did you choose and why?

Simply removed the restriction from the base class that only matched on principals of type user. Apart from the project filter, the meetings filter is inheriting from the base class, too. Therefore, this change alters meetings filters – in theory. In practice, there is no user custom field filter for meetings, so this change has no effect on meetings.

Merge checklist

• [x] Added/updated tests
• [ ] Added/updated documentation in Lookbook (patterns, previews, etc)
• [x] Tested major browsers (Chrome, Firefox, Edge, ...)