Bug 36816: Restore clearing patron attributes - OPAC

Bug 36816: Restore clearing patron attributes - OPAC

1) Add a new patron attribute type, visit:
<staff_url>/cgi-bin/koha/admin/patron-attr-types.pl?op=add_attribute_type
2) Add a code and a description (whatever) - Make it 'Display in OPAC' and 'Editable in OPAC'
3) Access OPAC patron personal details page, visit:
<opac_url>/cgi-bin/koha/opac-memberentry.pl
4) Scroll down and add some info to 'whatever'. Click 'Submit update request'.
5) Visit the INTRA 'update patron requests from opac' page:
<staff_url>/cgi-bin/koha/members/members-update.pl
6) Notice the entry is there. Select 'approve' and click "Submit"
7) Repeat 3)
8) Scroll down and notice the approved value is there. Clear that data and "Submit update request" (as if you're requesting for that data to be removed/cleared)
9) Repeat 5)
10) Notice there's an entry, and it is not empty. Select 'approve' and click "Submit"
11) Repeat 3)
12) Scroll down and notice the request to update (clear) that field did go through, i.e. the data is not there anymore.

Also test self-registration and mandatory attributes

Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit f4e999bb9f9a714eedc5bac22dd6902abe288af1)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>