Use confluence icon for Confluence service

https://gitlab.com/gitlab-org/gitlab/-/issues/220934

app/assets/images/confluence.svg

+<svg height="16" width="16" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><linearGradient id="a"><stop offset="0" stop-color="#344563"/><stop offset=".68" stop-color="#637088"/><stop offset="1" stop-color="#7a869a"/></linearGradient><linearGradient id="b" gradientUnits="userSpaceOnUse" x1="14.873" x2="5.739" xlink:href="#a" y1="15.883" y2="10.625"/><linearGradient id="c" gradientUnits="userSpaceOnUse" x1="-168376" x2="-168177" xlink:href="#a" y1="-6722.4" y2="-6493.53"/><path d="m1.517 11.68c-.15.243-.32.53-.453.757a.462.462 0 0 0 .155.63l3.013 1.863a.466.466 0 0 0 .645-.158l.445-.735c1.197-1.97 2.402-1.732 4.571-.703l2.995 1.424a.468.468 0 0 0 .626-.232l1.448-3.24a.466.466 0 0 0 -.229-.606c-.633-.298-1.89-.89-3.016-1.434-4.089-2.004-7.551-1.86-10.2 2.434z" fill="url(#b)"/><path d="m14.479 4.315c.15-.243.324-.53.456-.758a.46.46 0 0 0 -.158-.63l-3.025-1.857a.464.464 0 0 0 -.644.158 22.81 22.81 0 0 1 -.446.736c-1.196 1.972-2.4 1.733-4.567.703l-2.993-1.424a.468.468 0 0 0 -.625.231l-1.437 3.246a.46.46 0 0 0 .225.607c.633.298 1.892.89 3.014 1.435 4.097 1.99 7.556 1.858 10.199-2.446z" fill="url(#c)"/></svg>
\ No newline at end of file

app/views/layouts/nav/sidebar/_project.html.haml

@@ -298,7 +298,7 @@
         = nav_link do
           = link_to confluence_url, class: 'shortcuts-confluence' do
             .nav-icon-container
-              = sprite_icon('external-link')
+              = image_tag 'confluence.svg', alt: _('Confluence')
             %span.nav-item-name
               = _('Confluence')
           %ul.sidebar-sub-level-items.is-fly-out-only

changelogs/unreleased/220934-confluence-wiki-icon.yml

+---
+title: Use a Confluence icon for the project Confluence integration nav item
+merge_request: 36780
+author:
+type: changed