Plans page - Fixes the accessibility issues on the plans page (#20258)

* adding the li within ul to fix the accessibility issue from axe dev tools

* adding aria-label on the button

* adding a translation

GitOrigin-RevId: de46c7f1a71d7921b7ab88299441c50ef666cae2

services/web/frontend/stylesheets/app/plans/plans-new-design.less

@@ -812,6 +812,7 @@
 
         .plans-card-cta-container {
           margin-top: var(--spacing-08);
+          width: 100%;
 
           .btn-block + .btn-block {
             margin-top: var(--spacing-04);

services/web/locales/en.json

@@ -1211,6 +1211,7 @@
   "maximum_files_uploaded_together": "Maximum __max__ files uploaded together",
   "may": "May",
   "maybe_later": "Maybe later",
+  "member_picker": "Select number of users for group plan",
   "members_management": "Members management",
   "mendeley": "Mendeley",
   "mendeley_cta": "Get Mendeley integration",