Bug 29049: Simplify holds priority dropdown logic on request.pl

Bug 29049: Simplify holds priority dropdown logic on request.pl

This patch makes a few changes:
1 - If we are not splitting the queue ( HoldsSplitQueue == 'nothing' ) then
    there are no changes for 'virtual' vs 'actual' numbering
2 - If we are splitting the queue you cannot use the dropdown, so we do not need to process the options
3 - If the hold is 'found' we do not need to process the options
4 - We can simply use the 'last priority' to build the options, we do not need to process in the script
5 - We can use a block to build the options
6 - Remove a stray holds.index

To test:
 1 - Place 5 holds on a bib
 2 - 'Find' two of the holds i.e. check them in to set status to 'transit' or 'waiting'
 3 - View the holds page for the biblio
 4 - Inspect the priorty dropdown for the found holds, note they have options for 1-5 but are disabled
 5 - Note the dropdowns for other holds have options 1-5
 6 - Note options 4&5 in the dropdowns have no effect
 7 - Apply patch
 8 - Inspect the priority dopdowns on the found holds
 9 - Note they only show their found status
10 - Note the other dropdowns only show options 1-3
11 - Test with other HoldsSplitQueue options and HoldsSplitQueueNumbering
12 - When holds queue is split, no dropdowns should be active and should show only their current priority
13 - When  HoldsSplitQueueNumbering is 'virtual' the dropdown should be disabled and correctly count the number of unfound holds in the list

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
JK: Fixed grammar in commit title
Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
JD: Remove trailing 'i'

Bug 29049: (QA follow-up) Remove excessive whitespace

Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>