Bug 30878: Avoid resetting waiting reserves tab

Bug 30878: Avoid resetting waiting reserves tab

When canceling holds waiting over X days in "Holds awaiting pickup"
view, form submission resets the selected tab to "Holds waiting". This
tab reset may cause confusion for the user and lead to unwanted
actions. Instead, the user should be returned to the same tab that they
began with.

To test:
1. Apply patch
2. Navigate to /cgi-bin/koha/circ/waitingreserves.pl
3. Select "Holds waiting over X days" tab
4. Refresh page
5. Observe "Holds waiting over X days" is still selected
6. Have some holds waiting over X days
7. Select one of them and press "Cancel selected (1)" and confirm
8. Observe "Holds waiting over X days" is still selected after form
   submission

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>