Bug 36462: remove extra Home breadcrumb item

Bug 36462: remove extra Home breadcrumb item

In the Staff interface, when viewing (or editing) the authority MARC
subfield structure for a particular field, the Home button breadcrumb
on the top left of the screen appears twice.

This patch fixes that.

Test plan:
1) Try to view (or edit) the authority MARC subfield structure for
   a particular field. Notice the 'Home' breadcrumb button/icon is
   appearing twice.
2) Apply this patch.
3) Refresh the page, the 'Home' breadcrumb icon should now appear
   only once.

Signed-off-by: Esther <esther@bywatersolutions.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>