Bug 11955: Remove spaces in empty indicators when linking an authority to a biblio...

Bug 11955: Remove spaces in empty indicators when linking an authority to a biblio record.

This patch removes spaces in indicators which are imported when we link an
authority to a biblio record. The spaces made the indicators harder to edit
after the linking, because we had to delete the superfluous space character
before a new value could be entered.

To test:
1. Open some authority on editor, save with empty indicators.
   They are saved as ind1=" " ind2=" " on auth_header tables, with spaces
2. Edit some record, link some tag with previous auth,
   indicators now have a space on it (or ind1 at last)
3. Apply the patch
4. repeat 2, space is gone

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Work as described. No koha-qa errors.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit afc9549a6f58ddf36cf6d9a5399239385c377c90)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>