Replaced unused `new-gl-button` with `gl-button`

It looks like `new-gl-button` might have been
an old class. Either way, it doesn't exist
anymore, so let's get rid of it and migrate to
`gl-button` while we're at it.

app/assets/javascripts/behaviors/markdown/render_mermaid.js

@@ -140,7 +140,7 @@ function renderMermaids($els) {
                   'Warning: Displaying this diagram might cause performance issues on this page.',
                 )}</div>
                 <div class="gl-alert-actions">
-                  <button class="js-lazy-render-mermaid btn gl-alert-action btn-warning btn-md new-gl-button">Display</button>
+                  <button class="js-lazy-render-mermaid btn gl-alert-action btn-warning btn-md gl-button">Display</button>
                 </div>
               </div>
               <button type="button" class="close" data-dismiss="alert" aria-label="Close">

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

@@ -11,7 +11,7 @@
       %h4.gl-alert-title= s_('AdminSettings|Some settings have moved')
       = html_escape_once(s_('AdminSettings|Elasticsearch, PlantUML, Slack application, Third party offers, Snowplow, Amazon EKS have moved to Settings > General.')).html_safe
     .gl-alert-actions
-      = link_to s_('AdminSettings|Go to General Settings'), general_admin_application_settings_path, class: 'btn gl-alert-action btn-info new-gl-button'
+      = link_to s_('AdminSettings|Go to General Settings'), general_admin_application_settings_path, class: 'btn gl-alert-action btn-info gl-button'
 
 %h4= s_('AdminSettings|Apply integration settings to all Projects')
 %p

app/views/shared/_auto_devops_callout.html.haml

@@ -8,7 +8,7 @@
     %p
       - link = link_to(s_('AutoDevOps|Auto DevOps documentation'), help_page_path('topics/autodevops/index.md'), target: '_blank', rel: 'noopener noreferrer')
       = s_('AutoDevOps|Learn more in the %{link_to_documentation}').html_safe % { link_to_documentation: link }
-    = link_to s_('AutoDevOps|Enable in settings'), project_settings_ci_cd_path(@project, anchor: 'autodevops-settings'), class: 'btn btn-md new-gl-button js-close-callout'
+    = link_to s_('AutoDevOps|Enable in settings'), project_settings_ci_cd_path(@project, anchor: 'autodevops-settings'), class: 'btn btn-md btn-default gl-button js-close-callout'
 
   %button.gl-banner-close.close.js-close-callout{ type: 'button',
   'aria-label' => s_('AutoDevOps|Dismiss Auto DevOps box') }

app/views/shared/_no_ssh.html.haml

@@ -6,5 +6,5 @@
     .gl-alert-body
       = s_("MissingSSHKeyWarningLink|You won't be able to pull or push repositories via SSH until you add an SSH key to your profile")
     .gl-alert-actions
-      = link_to s_('MissingSSHKeyWarningLink|Add SSH key'), profile_keys_path, class: "btn gl-alert-action btn-warning btn-md new-gl-button"
+      = link_to s_('MissingSSHKeyWarningLink|Add SSH key'), profile_keys_path, class: "btn gl-alert-action btn-warning btn-md gl-button"
       = link_to s_("MissingSSHKeyWarningLink|Don't show again"), profile_path(user: {hide_no_ssh_key: true}), method: :put, role: 'button', class: 'btn gl-alert-action btn-md btn-warning gl-button btn-warning-secondary'

changelogs/unreleased/ps-clean-new-gl-button-refs.yml

+---
+title: Update button style for consistency in Settings > Integrations, Mermaid Diagram
+  warning, and No SSH warning
+merge_request: 51864
+author:
+type: other