[EuiDataGrid] use schema sorting labels instead of placeholder value

[chandlerprall]

Summary

Came up again in #4197 but also reported in slack last week, the recently added column actions used placeholder copy for sort text instead of using the column schema's labels.

I opted to nest the existing i18n'd labels (A-Z, High-Low) into a new i18n token which prepends Sort . I think this combines the best of re-usability while retaining flexibility for downstream consuming applications. I confirmed these overrides work as expected (see below).

Before

After

Localized schema labels

      i18n={{
        mapping: {
          'euiColumnSortingDraggable.defaultSortAsc': 'Going down',
          'euiColumnSortingDraggable.defaultSortDesc': 'Going up',
          'euiDataGridSchema.currencySortTextAsc': 'Increasing',
          'euiDataGridSchema.currencySortTextDesc': 'Decreasing',
        },
      }}

Localized schema + sort labels

      i18n={{
        mapping: {
          'euiColumnSortingDraggable.defaultSortAsc': 'Going down',
          'euiColumnSortingDraggable.defaultSortDesc': 'Going up',
          'euiDataGridSchema.currencySortTextAsc': 'Increasing',
          'euiDataGridSchema.currencySortTextDesc': 'Decreasing',
          'euiColumnActions.sort': 'Order: {schemaLabel}',
        },
      }}

Checklist

- [ ] Check against all themes for compatibility in both light and dark modes
- [ ] Checked in mobile
- [ ] Checked in Chrome, Safari, Edge, and Firefox
- [ ] Props have proper autodocs
- [ ] Added documentation
- [ ] Checked Code Sandbox works for the any docs examples

• Added or updated jest tests
• Checked for breaking changes and labeled appropriately
  - [ ] Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4199/

[thompsongl]

I opted to nest the existing i18n'd labels (A-Z, High-Low) into a new i18n token which prepends Sort

I agree this is a good approach.

Confirmed the new labels in the docs preview.

Need to updated some snapshots and add a changelog entry, but otherwise LGTM

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_4199/