Update spinner for ssh_host_keys partial

* Update to use pajamas compliant spinner

app/assets/javascripts/mirrors/ssh_mirror.js

@@ -76,7 +76,7 @@ export default class SSHMirror {
 
     // Disable button while we make request
     this.$btnDetectHostKeys.disable();
-    $btnLoadSpinner.removeClass('d-none');
+    $btnLoadSpinner.removeClass('gl-display-none');
 
     // Make backOff polling to get data
     backOff((next, stop) => {
@@ -101,7 +101,7 @@ export default class SSHMirror {
         .catch(stop);
     })
       .then((res) => {
-        $btnLoadSpinner.addClass('d-none');
+        $btnLoadSpinner.addClass('gl-display-none');
         // Once data is received, we show verification info along with Host keys and fingerprints
         this.$hostKeysInformation
           .find('.js-fingerprint-verification')

app/views/projects/mirrors/_ssh_host_keys.html.haml

@@ -4,7 +4,7 @@
 
 .form-group.js-ssh-host-keys-section{ class: ('collapse' unless mirror.ssh_mirror_url?) }
   %button.btn.gl-button.btn-inverted.btn-secondary.inline.js-detect-host-keys.gl-mr-3{ type: 'button', data: { qa_selector: 'detect_host_keys' } }
-    .js-spinner.d-none.gl-spinner.mr-1
+    = gl_loading_icon(inline: true, css_class: 'js-spinner gl-display-none gl-mr-2')
     = _('Detect host keys')
   .fingerprint-ssh-info.js-fingerprint-ssh-info.gl-mt-3.gl-mb-3{ class: ('collapse' unless mirror.ssh_mirror_url?) }
     %label.label-bold