Disable download action logs button when there's no logs (#26114)

If there's no logs, you can also click the download button, then you
will get `job is not started` page

![image](https://github.com/go-gitea/gitea/assets/18380374/c0dad309-1fb9-4505-99da-bf0038423744)
https://gitea.com/yp05327/testrepo/actions/runs/38

After:
If there's no steps displayed, the download button will be disabled.

![image](https://github.com/go-gitea/gitea/assets/18380374/5f51ba70-3d0b-46d8-ad77-f02c4c8fa52c)

Author: yp05327

web_src/js/components/RepoActionView.vue

@@ -74,7 +74,7 @@
                 <SvgIcon name="octicon-gear" :size="18"/>
               </button>
               <div class="menu transition action-job-menu" :class="{visible: menuVisible}" v-if="menuVisible" v-cloak>
-                <a class="item" :href="run.link+'/jobs/'+jobIndex+'/logs'" target="_blank">
+                <a :class="['item', currentJob.steps.length === 0 ? 'disabled' : '']" :href="run.link+'/jobs/'+jobIndex+'/logs'" target="_blank">
                   <i class="icon"><SvgIcon name="octicon-download"/></i>
                   {{ locale.downloadLogs }}
                 </a>