Bug 28847: Cleanup of branch limitsand fix OPAC_SEARCH_LIMIT

Bug 28847: Cleanup of branch limitsand fix OPAC_SEARCH_LIMIT

The opac had 'branch_group_limit' parameters which can be simplified to more
closely match intranet code.

Adjust C4::Auth for chaneg above to ensure dropdowns correctly populate

Expand JS to prevent selection of single and multibranch limits

To test:
1 - Enable OpacAddMastheadLibraryPulldown system preference
2 - Ensure branches and groups show as before patch
3 - Ensure single and multibranch limits from masthead apply as expected
4 - Test advanced search page, ensure you cannot select both single and multibranch limit
5 - Follow test plan on 28845 - ensure multibranch limit still correctly pre-selected

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>