Bug 32301: Fix default search sorting in advanced search when not editing a search

Bug 32301: Fix default search sorting in advanced search when not editing a search

Bug 22605 changed the sorting to expect the passed parameter from the
previous search, this broke default when the search page was loaded
fresh.

We should simply fallback from the edited search to the default if it is
not set

To test:
1) Go to staff client
2) Go to Advanced Search
3) Notice the default Sort By value is "Relevance"
4) Go to system preferences
5) Go to "defaultSortField"
6) Change the value of the system preference
7) Go back to Advanced Search and refresh the page
8) Notice that there are no changes, the default Sort By is still
"Relevance"
9) Apply patch
10) Notice that changing the system preference now changes the default
Sort By in Advanced Search
11) Perform a search, change the sorting, then edit the search
12) Confirm the correct sorting from the search is preserved

Signed-off-by: Michaela Sieber <michaela.sieber@kit.edu>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>