chore: make control panel sub sections look better (#24736)

superset-frontend/plugins/plugin-chart-echarts/src/MixedTimeseries/controlPanel.tsx

@@ -23,6 +23,7 @@ import {
   ControlPanelConfig,
   ControlPanelSectionConfig,
   ControlSetRow,
+  ControlSubSectionHeader,
   CustomControlItem,
   getStandardizedControls,
   sections,
@@ -128,7 +129,7 @@ function createCustomizeSection(
   controlSuffix: string,
 ): ControlSetRow[] {
   return [
-    [<div className="section-header">{label}</div>],
+    [<ControlSubSectionHeader>{label}</ControlSubSectionHeader>],
     [
       {
         name: `seriesType${controlSuffix}`,
@@ -311,7 +312,7 @@ const config: ControlPanelConfig = {
           },
         ],
         ...legendSection,
-        [<div className="section-header">{t('X Axis')}</div>],
+        [<ControlSubSectionHeader>{t('X Axis')}</ControlSubSectionHeader>],
         ['x_axis_time_format'],
         [
           {
@@ -335,7 +336,7 @@ const config: ControlPanelConfig = {
         ],
         ...richTooltipSection,
         // eslint-disable-next-line react/jsx-key
-        [<div className="section-header">{t('Y Axis')}</div>],
+        [<ControlSubSectionHeader>{t('Y Axis')}</ControlSubSectionHeader>],
         [
           {
             name: 'minorSplitLine',