fix(pie): apply percentage number formats to pie chart labels

[Kr1dhay]

SUMMARY

Fixes #42834.

On a pie chart, setting Labels → Percentage and then choosing a Number format had no effect on the percentage label. The percent formatter was a hardcoded module constant:

// Pie/transformProps.ts
const percentFormatter = getNumberFormatter(NumberFormats.PERCENT_2_POINT);

number_format only ever reached numberFormatter, so the percent half of every label was pinned to ,.2%.

This implements approach #2 from the issue thread, which the reporter asked for: the number_format control now drives percentage labels when the selected format is a percentage D3 format (,.1%, .0%, …). Any other format — SMART_NUMBER, currency, ,d — keeps the existing two-decimal default.

The type check matters for backwards compatibility: applying a value format such as ,d to a fraction would render 12.34% as 0. Gating on the format type means no existing chart changes output; only a user who deliberately picks a % format sees a difference.

Detection uses .includes('%'), the idiom already used for this purpose in sharedControls.tsx (y_axis_format, x_axis_number_format).

The change covers every percent-bearing surface, since they all share one formatter: the four percent label types (percent, key_percent, key_value_percent, value_percent), the template label type's {percent}, tooltips, and the "Other" bucket rows.

One consequence worth calling out: because a single control drives both halves of the label, picking a % format also formats the value half as a percentage. That is inherent to reusing number_format rather than adding a second control — happy to switch to a dedicated percentage_format control if maintainers prefer that shape.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

Automated — superset-frontend/plugins/plugin-chart-echarts/test/Pie/transformProps.test.ts:

cd superset-frontend
npx jest plugins/plugin-chart-echarts/test/Pie/transformProps.test.ts

Four cases added: parseParams honours an injected percent formatter; a % number format reaches the label; a non-% format leaves the percentage at ,.2% (the backwards-compatibility guard); and the template label type picks up the format. The pre-existing should be formatted using the number formatter test already asserts ,d leaves percentages at 55.50% and still passes unchanged.

Manual:

1. Create a Pie chart with a dimension and a metric.
2. Set Labels → Label Type to Category and Percentage.
3. Set Number format to ,.1% → percentages render with one decimal (12.3%).
4. Set it back to SMART_NUMBER or ,d → percentages return to 12.34%, exactly as before this change.

ADDITIONAL INFORMATION

• Has associated issue: Pie Charts do not format Percentage values correctly #42834
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

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