Test should-render target mappings for product configuration extensions

[one20]

WHY are these changes introduced?

Fixes https://github.com/shop/issues-on-ramps/issues/900

The CLI target mapping needs regression coverage for the two product configuration surfaces that expose a render target with a corresponding should-render target. UI Extensions Shopify/ui-extensions#4600 and Core https://github.com/shop/issues-on-ramps/issues/899 are separate dependencies for this work.

WHAT is this pull request doing?

Adds focused tests for getShouldRenderTarget covering these target conversions:

• admin.product-details.configuration.render → admin.product-details.configuration.should-render
• admin.product-variant-details.configuration.render → admin.product-variant-details.configuration.should-render

UI Extensions Shopify/ui-extensions#4600 and Core https://github.com/shop/issues-on-ramps/issues/899 remain separate dependencies and are not included in this CLI-only change.

How to test your changes?

• pnpm --filter @shopify/app vitest run src/cli/models/extensions/specifications/ui_extension.test.ts — 55 tests passed
• pnpm --filter @shopify/app type-check — passed
• pnpm --filter @shopify/app lint — passed
• git diff --check — passed

Post-release steps

No post-release steps.

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add (not applicable; test-only change)