fix: Data source picker in panel queries options should overlap content below,…

fix: Data source picker in panel queries options should overlap content below, including ace scrollbar #15122

public/sass/components/_toolbar.scss

@@ -4,7 +4,6 @@
   align-items: center;
   padding: 3px 20px 3px 20px;
   position: relative;
-  z-index: 1;
   flex: 0 0 auto;
   background: $toolbar-bg;
   border-radius: 3px;