Fix clazy 'connect-3arg-lambda' warnings
Summary: The recommendation is to use the 4-arg overload, which takes a context object so that the lambda isn't executed when the context object is deleted.
Reviewers: KDevelop, kfunk
Reviewed By: KDevelop, kfunk
Subscribers: kfunk, kdevelop-devel
Tags: KDevelop
Differential Revision: https://phabricator.kde.org/D14996