Bug 36156: None value selected on clone field/subfield linked to AV

Bug 36156: None value selected on clone field/subfield linked to AV

When a field or subfield is linked to a list of authorized values and cloned, the selected value is repeated in the clone. This is linked to the default behavior of Select2Utils, so I've added a precise index (-1) to ensure that no value is selected in the clone.

Test plan:

1) Create a repeatable field and subfield and link a list of authorised values to the subfield.
2) Edit a record, clone the field and see which value is automatically selected in the clone.
3) Apply the patch
4) Repeat step 2

Sponsored by : BibLibre

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>