ConfigPageForm in Djblets fetches a user profile up-front, which the

subclasses then use to access profile state. That functionality is

deprecated, as profiles are no longer a core part of Django. An upcoming

change will raise a DeprecationWarning any time self.profile is

accessed.
This change prepares for that by fetching the profile on-demand instead

of using the attribute lookup. Since profiles are cached, this won't

result in any extra database access.

Unit tests pass.
Manually tested loading and saving settings on the affected forms.