Hid total member counts in newsletter selection for authors/editors

no issue

- authors/editors don't yet have a way to fetch member counts for specific filters so the final member count is hidden in the publish options text, however we were still showing the total subscribed members for each newsletter in the dropdown which could lead to incorrect assumptions for how many members would receive the newsletter

ghost/admin/app/components/editor-labs/publish-options/email-recipients.hbs

@@ -6,7 +6,7 @@
         @renderInPlace={{false}}
         @dropdownClass="gh-publish-newsletter-dropdown"
     />
-    
+
     {{#if (gt @publishOptions.newsletters.length 1)}}
         <div class="mt4">
             <label class="gh-main-section-header small bn">Newsletter</label>
@@ -19,7 +19,11 @@
                 @dropdownClass="gh-publish-newsletter-dropdown"
                 as |newsletter|
             >
-                <span>{{newsletter.name}}</span><span class="gh-newsletter-count">{{format-number newsletter.count.members}}</span>
+                <span>{{newsletter.name}}</span>
+                {{!-- TODO: remove conditional when author/editor can fetch member counts --}}
+                {{#if @publishOptions.user.isAdmin}}
+                    <span class="gh-newsletter-count">{{format-number newsletter.count.members}}</span>
+                {{/if}}
             </PowerSelect>
         </div>
     {{/if}}