ECharts Bar Chart renders only currency symbol ($) when Show Value is enabled with stacked bars

### Bug description

Superset version:
5.0.0

Chart type:
ECharts Bar Chart

Configuration:
- Stacked bar
- Show Value enabled
- Currency prefix ($)
- Near-zero negative values
- Row limit: 50

Steps to reproduce:
1. Create dataset with mostly small negative values (e.g. -1 to -5)
2. Add one large negative outlier (e.g. -4,000,000)
3. Create ECharts Bar Chart
4. Enable stacked bars
5. Enable "Show Value"
6. Apply currency prefix ($)

Expected behavior:
Numeric values should render correctly with currency formatting (e.g., $1,234), and should not display only the currency symbol.

Actual behavior:
Only the currency symbol "$" is rendered repeatedly without numeric values, particularly for near-zero values.
Occurs in both horizontal and vertical orientation.

[warehouse_handling_dummy_data.csv](https://github.com/user-attachments/files/25383785/warehouse_handling_dummy_data.csv)

Browser:
Google Chrome 143.0.7499.193 (Official Build) (arm64)

### Screenshots/recordings

_No response_

### Superset version

master / latest-dev

### Python version

3.9

### Node version

16

### Browser

Chrome

### Additional context

_No response_

### Checklist

- [x] I have searched Superset docs and Slack and didn't find a solution to my problem.
- [x] I have searched the GitHub issue tracker and didn't find a similar bug report.
- [x] I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.

Reproduce the issue in an ECharts Bar Chart using the supplied warehouse_handling_dummy_data.csv and the listed stacked-bar, Show Value, and currency settings. Start by tracing the chart's value-label formatting entry point in the frontend; done means near-zero and large negative values display numeric currency labels rather than only "$" in both orientations.

Written by the indexing model from the issue text.