Cleanup container css for Geo Nodes

This mainly goes back to a simple top down flow on the headers
Instead of using floats and fixed margins

Use margin over flex grow

Decouple button and h2

ee/app/assets/stylesheets/pages/geo_nodes.scss

-.geo-admin-container {
-  .page-title,
-  .page-title-separator {
-    margin-top: 10px;
-  }
-
-  .title-text {
-    line-height: 34px;
-  }
-
-  .page-subtitle {
-    margin-bottom: 24px;
-  }
-}
-
 .node-badge {
   color: $white-light;
   padding: 1px $gl-padding-8;

ee/app/views/admin/geo/designs/index.html.haml

 - page_title _('Geo Designs')
-- @content_class = "geo-admin-container"
 
 #js-geo-designs{ data: { "geo-svg-path" => image_path('illustrations/gitlab_geo.svg'),
   "issues-svg-path" => image_path('illustrations/issues.svg'),

ee/app/views/admin/geo/nodes/index.html.haml

 - page_title 'Geo Nodes'
-- @content_class = "geo-admin-container"
 
 = render_enable_hashed_storage_warning
 = render_migrate_hashed_storage_warning
 
-%h2.page-title.clearfix
-  %span.title-text.float-left= _("Geo Nodes")
-  = link_to s_("GeoNodes|New node"), new_admin_geo_node_path, class: 'btn btn-success float-right qa-new-node-link'
-%hr.page-title-separator
+.d-flex.align-items-center.border-bottom.border-default.mb-4
+  %h2.page-title
+    = _("Geo Nodes")
+  = link_to s_("GeoNodes|New node"), new_admin_geo_node_path, class: 'btn btn-success ml-auto qa-new-node-link'
 
 %p.page-subtitle.light
   = s_('GeoNodes|With %{geo} you can install a special read-only and replicated instance anywhere. Before you add nodes, follow the %{instructions} in the exact order they appear.').html_safe % { geo: link_to('GitLab Geo', help_page_path('administration/geo/replication/index.md'), target: '_blank'), instructions: link_to('setup instructions', help_page_path('administration/geo/replication/index.md', anchor: 'setup-instructions'), target: '_blank') }

ee/app/views/admin/geo/nodes/new.html.haml

 - page_title 'New node'
-- @content_class = "geo-admin-container"
 
 %h2.page-title
   %span.title-text

ee/app/views/admin/geo/projects/index.html.haml

 - page_title 'Geo Projects'
-- @content_class = "geo-admin-container geo-admin-projects"
+- @content_class = "geo-admin-projects"
 - params[:sync_status] ||= []
 
 .top-area.scrolling-tabs-container.inner-page-scroll-tabs

ee/app/views/admin/geo/settings/show.html.haml

 - page_title "Geo Settings"
-- @content_class = "limit-container-width geo-admin-container geo-admin-settings" unless fluid_layout
+- @content_class = "limit-container-width geo-admin-settings" unless fluid_layout
 
 = render_if_exists 'admin/geo/settings/form'

ee/app/views/admin/geo/uploads/index.html.haml

 - page_title 'Geo Uploads'
-- @content_class = "geo-admin-container geo-admin-uploads"
+- @content_class = "geo-admin-uploads"
 - params[:sync_status] ||= []
 
 %div{ class: container_class }