Bug 34646: Fix two attributes class in OPAC masthead-langmenu.inc

Bug 34646: Fix two attributes class in OPAC masthead-langmenu.inc

In OPAC template masthead-langmenu.inc a link as two class attributes :
  <a class="dropdown-item" href="#" tabindex="-1" class="menu-inactive" role="menuitem">

Test plan :
1) Go to OPAC with at least one translation
2) Look at HTML source code
=> Without patch you see a link with 2 class attributes
=> With patch you see the 2 classes in same class attribute

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>