Bug 33734: Remove incorrect URL escaping on search filters

Bug 33734: Remove incorrect URL escaping on search filters

This patch removes an incorrect URL escaping on search filter
facet URLs.

Without this patch, search filters using non-ASCII characters won't
return results.

To test:
0. Apply patch
1. Enable SavedSearchFilters syspref
2. Search for "the"
3. Save as search filter (to show on both OPAC and staff interface)
4. Search for "ü" in staff interface
5. Apply the "the" filter
6. Note that search results appear
7. Search for "ü" in OPAC
8. Apply the "the" filter
9. Note that search results appear

Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>