fix(charts): update axis title labels to sentence case

Changed "AXIS TITLE MARGIN" and "AXIS TITLE POSITION" labels
from ALL CAPS to proper sentence case in bar and bubble charts.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

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

@@ -142,7 +142,7 @@ const config: ControlPanelConfig = {
               type: 'SelectControl',
               freeForm: true,
               clearable: true,
-              label: t('X AXIS TITLE MARGIN'),
+              label: t('X axis title margin'),
               renderTrigger: true,
               default: sections.TITLE_MARGIN_OPTIONS[1],
               choices: formatSelectOptions(sections.TITLE_MARGIN_OPTIONS),
@@ -214,7 +214,7 @@ const config: ControlPanelConfig = {
               type: 'SelectControl',
               freeForm: true,
               clearable: true,
-              label: t('Y AXIS TITLE MARGIN'),
+              label: t('Y axis title margin'),
               renderTrigger: true,
               default: sections.TITLE_MARGIN_OPTIONS[1],
               choices: formatSelectOptions(sections.TITLE_MARGIN_OPTIONS),

superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/Regular/Bar/controlPanel.tsx

@@ -81,7 +81,7 @@ function createAxisTitleControl(axis: 'x' | 'y'): ControlSetRow[] {
           type: 'SelectControl',
           freeForm: true,
           clearable: true,
-          label: t('AXIS TITLE MARGIN'),
+          label: t('Axis title margin'),
           renderTrigger: true,
           default: sections.TITLE_MARGIN_OPTIONS[0],
           choices: formatSelectOptions(sections.TITLE_MARGIN_OPTIONS),
@@ -114,7 +114,7 @@ function createAxisTitleControl(axis: 'x' | 'y'): ControlSetRow[] {
           type: 'SelectControl',
           freeForm: true,
           clearable: true,
-          label: t('AXIS TITLE MARGIN'),
+          label: t('Axis title margin'),
           renderTrigger: true,
           default: sections.TITLE_MARGIN_OPTIONS[1],
           choices: formatSelectOptions(sections.TITLE_MARGIN_OPTIONS),
@@ -132,7 +132,7 @@ function createAxisTitleControl(axis: 'x' | 'y'): ControlSetRow[] {
           type: 'SelectControl',
           freeForm: true,
           clearable: false,
-          label: t('AXIS TITLE POSITION'),
+          label: t('Axis title position'),
           renderTrigger: true,
           default: sections.TITLE_POSITION_OPTIONS[0][0],
           choices: sections.TITLE_POSITION_OPTIONS,