Improve accessibility of Admin application settings page

by removing placeholder from textarea

Changelog: changed

app/views/admin/application_settings/_note_limits.html.haml

@@ -7,8 +7,8 @@
       = f.number_field :notes_create_limit, class: 'form-control gl-form-input'
     .form-group
       = f.label :notes_create_limit_allowlist, _('Users to exclude from the rate limit'), class: 'label-bold'
-      = f.text_area :notes_create_limit_allowlist_raw, placeholder: 'username1, username2', class: 'form-control gl-form-input', rows: 5
-      .form-text.text-muted
+      = f.text_area :notes_create_limit_allowlist_raw, class: 'form-control gl-form-input', rows: 5, aria: { describedBy: 'note-create-limits-allowlist-field-description' }
+      .form-text.text-muted{ id: 'note-create-limits-allowlist-field-description' }
         = _('List of users allowed to exceed the rate limit.')
 
 

app/views/admin/application_settings/_users_api_limits.html.haml

@@ -7,8 +7,8 @@
       = f.number_field :users_get_by_id_limit, class: 'form-control gl-form-input'
     .form-group
       = f.label :users_get_by_id_limit_allowlist_raw, _('Users to exclude from the rate limit'), class: 'label-bold'
-      = f.text_area :users_get_by_id_limit_allowlist_raw, placeholder: 'username1, username2', class: 'form-control gl-form-input', rows: 5
-      .form-text.text-muted
+      = f.text_area :users_get_by_id_limit_allowlist_raw, class: 'form-control gl-form-input', rows: 5, aria: { describedBy: 'users-api-limit-users-allowlist-field-description' }
+      .form-text.text-muted{ id: 'users-api-limit-users-allowlist-field-description' }
         = _('List of users allowed to exceed the rate limit.')
 
   = f.submit _('Save changes'), class: "gl-button btn btn-confirm", data: { qa_selector: 'save_changes_button' }