SessionPool: set the namespaces variables from the namespace job.

Summary:
This was there in the initial commit that introduced these variables
but got lost somehow (merge conflict resolution I think)

Fixes the time loss and noise from the kolab resource on startup:
MyRights failed: "MyRights failed, server replied: A000869 NO Mailbox does not exist "

Test Plan: watching debug output from kolab resource on startup

Reviewers: dvratil, cmollekopf, knauss, vkrause

Reviewed By: vkrause

Subscribers: KDE PIM

Tags: KDE PIM

Differential Revision: https://phabricator.kde.org/D5347