fix(chart & heatmap): make to fix that y label is rendering out of bounds (#20011)

Author: prosdev0107

superset-frontend/plugins/legacy-plugin-chart-heatmap/src/Heatmap.js

@@ -111,7 +111,7 @@ function Heatmap(element, props) {
   let showY = true;
   let showX = true;
   const pixelsPerCharX = 4.5; // approx, depends on font size
-  const pixelsPerCharY = 6; // approx, depends on font size
+  let pixelsPerCharY = 6; // approx, depends on font size
 
   const valueFormatter = getNumberFormatter(numberFormat);
 
@@ -121,6 +121,7 @@ function Heatmap(element, props) {
     let longestY = 1;
 
     records.forEach(datum => {
+      if (typeof datum.y === 'number') pixelsPerCharY = 7;
       longestX = Math.max(
         longestX,
         (datum.x && datum.x.toString().length) || 1,