[v11.0.x] Tooltips: Ensure new viz tooltips are visible within modals (alternative solution) (#86954)

Tooltips: Ensure new viz tooltips are visible within modals (alternative solution) (#86716)

fix: ensure new viz tooltips are visible within modals

Co-authored-by: Leon Sorokin <leeoniya@gmail.com>
(cherry picked from commit ff761bb7d6)

packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin2.tsx

@@ -574,7 +574,7 @@ const getStyles = (theme: GrafanaTheme2, maxWidth?: number, maxHeight?: number)
   tooltipWrapper: css({
     top: 0,
     left: 0,
-    zIndex: theme.zIndex.tooltip,
+    zIndex: theme.zIndex.portal,
     whiteSpace: 'pre',
     borderRadius: theme.shape.radius.default,
     position: 'fixed',