Update confirmation button label as per terminology standards

app/views/projects/branches/index.html.haml

@@ -16,7 +16,7 @@
         class: 'gl-button btn btn-danger btn-danger-secondary has-tooltip qa-delete-merged-branches',
         title: s_("Branches|Delete all branches that are merged into '%{default_branch}'") % { default_branch: @project.repository.root_ref },
         method: :delete,
-        aria: { label: _('Delete') },
+        aria: { label: s_('Branches|Delete merged branches') },
         data: { confirm: s_('Branches|Deleting the merged branches cannot be undone. Are you sure?'),
           confirm_btn_variant: 'danger',
           container: 'body' } do