[spring-data-support] remove pure `findBy` method completion from proposal list

[martinlippert]

I am trying Petclinic, opened OwnerRepository, typing findBy and invoking content-assist. The list of proposals include a proposal findBy that produces

List<Owner> findBy();

which doesn't make a lot of sense. I think the code completion engine should not create this proposal.

[BoykoAlex]

Hopefully fixed with 3330e4e