Update SAML clipboard button

What does this MR do and why?

Update SAML clipboard button

• use pajamas button
• I didn't add any other button conversions to this MR because this button is bit of an odd one since it is so hard to test

Changelog: changed

EE: true

Screenshots or screen recordings

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Testing SAML locally is hard, so I hacked it a bit (like last time). Copy the code below and navigate to any project

diff --git a/app/views/projects/_home_panel.html.haml b/app/views/projects/_home_panel.html.haml
index 759ec541af56..f00b0096e673 100644
--- a/app/views/projects/_home_panel.html.haml
+++ b/app/views/projects/_home_panel.html.haml
@@ -2,6 +2,12 @@
 - show_auto_devops_callout = show_auto_devops_callout?(@project)
 - emails_disabled = @project.emails_disabled?
 
+.js-file-title.file-title
+= s_("GroupSAML|SAML Response XML")
+.file-actions
+  .btn-group
+    = clipboard_button(text: 'Test', class: "js-copy-blob-source-btn", title: s_('GroupSAML|Copy SAML Response XML'))
+
 .project-home-panel.js-show-on-project-root.gl-mt-4.gl-mb-5{ class: [("empty-project" if empty_repo)] }
   .gl-display-flex.gl-justify-content-space-between.gl-flex-wrap.gl-sm-flex-direction-column.gl-mb-3.gl-gap-5
     .home-panel-title-row.gl-display-flex.gl-align-items-center

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #417859 (closed)