Bug 36453: (QA follow-up) Cosmetic fixes

Bug 36453: (QA follow-up) Cosmetic fixes

This is a squash of several improvements:
- Override weird blue color being applied from MultipleSelect when all options from an optgroup are selected;
- Fix input width depending on selected value. Now it should always be same width regardless;
- Updated the system preference UI wording to reflect new behavior;
- Updated UI labels in the patron category edit page to enforce that the actions being selected are "actions to be blocked"
- Corrected sysprefs.sql entry

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>