Remove titles from security-links in sidebars

Both top-level navigation items that link to the projects'
and the group's security dashboard contain title-attributes.

This is inconsistent with the rest of the navigation.

This commit removes the title-attributes for both elements.

ee/app/views/layouts/nav/ee/_security_link.html.haml

 - if @group.feature_available?(:security_dashboard)
   = nav_link(path: 'groups/security/dashboard#show') do
-    = link_to group_security_dashboard_path(@group), title: _('Security'), data: { qa_selector: 'security_dashboard_link' } do
+    = link_to group_security_dashboard_path(@group), data: { qa_selector: 'security_dashboard_link' } do
       .nav-icon-container
         = sprite_icon('shield')
       %span.nav-item-name

ee/app/views/layouts/nav/sidebar/_project_security_link.html.haml

 - if project_nav_tab?(:security)
   = nav_link(path: sidebar_security_paths) do
-    = link_to project_security_dashboard_path(@project), title: _('Security Dashboard'), data: { qa_selector: 'link_security_dashboard' } do
+    = link_to project_security_dashboard_path(@project), data: { qa_selector: 'link_security_dashboard' } do
       .nav-icon-container
         = sprite_icon('shield')
       %span.nav-item-name