Bug 11578: (follow-up) fix funds grouping

Bug 11578: (follow-up) fix funds grouping

The datatables sort options were wrong.
The funds for a budget could be ungrouped.
To reproduce:
- Create 3 budgets A, B, C.
- Create 1 or more funds for A, B, C
- Mark B and C as inactive.
- Create another fund for A
- Go on the fund list view, click on "show inactive funds"
=> The last fund is not grouped without other funds of budget A.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>