Save HA Limit Enable checkbox

Summary:
The HA Limit checkbox saving method call was commented out.
I'm assuming this was an oversight, but please reject this PR if I'm wrong.

Test Plan:
Enable or disable the HA Limit checkbox in the mount tab.
Check should be enabled/disabled across sessions.

Reviewers: mutlaqja, chrisrowland

Reviewed By: mutlaqja

Subscribers: kde-edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D29471