Enable `@<user>`- completion popup on the release description textarea (#22359)

For some unknown reason, this was previously disabled.
Additionally removed an unused return value.

routers/web/repo/release.go

 		}
 	}
 	ctx.Data["IsAttachmentEnabled"] = setting.Attachment.Enabled
+	var err error
+	// Get assignees.
+	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, ctx.Repo.Repository)
+	if err != nil {
+		ctx.ServerError("GetAssignees", err)
+		return
+	}
+
 	upload.AddUploadContext(ctx, "release")
 	ctx.HTML(http.StatusOK, tplReleaseNew)
 }
 	}
 	ctx.Data["attachments"] = rel.Attachments
 
+	// Get assignees.
+	ctx.Data["Assignees"], err = repo_model.GetRepoAssignees(ctx, rel.Repo)
+	if err != nil {
+		ctx.ServerError("GetAssignees", err)
+		return
+	}
+
 	ctx.HTML(http.StatusOK, tplReleaseNew)
 }
 

web_src/js/features/repo-release.js

 export function initRepoReleaseEditor() {
   const $editor = $('.repository.new.release .content-editor');
   if ($editor.length === 0) {
-    return false;
+    return;
   }
 
   (async () => {
     const $textarea = $editor.find('textarea');
-    await attachTribute($textarea.get(), {mentions: false, emoji: true});
+    await attachTribute($textarea.get(), {mentions: true, emoji: true});
     const easyMDE = await createCommentEasyMDE($textarea);
     initCompMarkupContentPreviewTab($editor);
     const $dropzone = $editor.parent().find('.dropzone');