Fixed issue boards sidebar close button with new navigation

Closes #35296

app/assets/stylesheets/pages/boards.scss

@@ -431,7 +431,10 @@
   margin: 5px;
 }
-.page-with-layout-nav.page-with-sub-nav .issue-boards-sidebar {
+.page-with-layout-nav.page-with-sub-nav .issue-boards-sidebar,
+.page-with-new-sidebar.page-with-sidebar .issue-boards-sidebar {
+  position: absolute;
+
   &.right-sidebar {
     top: 0;
     bottom: 0;

changelogs/unreleased/issue-boards-close-icon-size.yml

+---
+title: Fixed issue boards sidebar close icon size
+merge_request:
+author: