refactor: 💡 update all header tags to use HDS::Text::Display (#2765)

* refactor: 💡 update all header tags to use HDS::Text::Display

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-16863

* refactor: 💡 update minor css changes for page header

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-16863

* refactor: 💡 remove duplicate title and lint hbs files

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-16863

ui/admin/app/components/auth-methods/auth-method/managed-groups/managed-group/header/index.hbs

@@ -3,9 +3,9 @@
   SPDX-License-Identifier: BUSL-1.1
 }}
 
-<h2>
+<Hds::Text::Display @tag='h2' @size='400' @weight='bold' class='header-spacing'>
   {{t 'resources.managed-group.title'}}
   <DocLink @doc='managed-groups' @iconSize='large' />
-</h2>
+</Hds::Text::Display>
 <p>{{t 'resources.managed-group.description'}}</p>
 <Hds::Copy::Snippet @textToCopy={{@model.id}} @color='secondary' />