UI Freeze Exception: software-properties removal of Ubuntu Pro settings

[Robert Ancell]

Hi

Due to backend delay, we want to remove the Ubuntu Pro settings in
software-properties and only show Livepatch settings as were previously
shown. This feature will be re-added at a future time.

This change will rename the "Ubuntu Pro" page to "Livepatch" and hide
various UI elements. This adds the following new strings for translations:
"This machine is not covered by an Ubuntu Advantage subscription."
"Ubuntu Advantage subscription attached."
"Livepatch"

All existing strings for the Ubuntu Pro settings remain, so should remain
translated when this change is reverted.
See
https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1965993
for more details.

Thanks,
--Robert