Bug 7180: make neworderempty code use getAuthValueDropbox.

Bug 7180: make neworderempty code use getAuthValueDropbox.

The js function fetchSortDropbox has been deleted in previous patch.
The new function is getAuthValueDropbox.

Test plan:
- link authorized values to some funds
- open an existing order and verify value are correctly filled in the
  sort1 and sort2 values
- create a new order and verify behavior is the same as before

Note: This patch generates 2 ajax queries (max) if the budget is linked
to 2 av categories for sort1 and sort2. This could be improved using a
template plugin for values display on load.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>