The conformance lane runs without WORKFLOW_VERCEL_ENV, so the retention
describe is skipped at collection time and the unsupported entry never
reaches requireSupported. assertUnsupportedTestsExist then reads it as
covering a test that no longer exists and fails the suite.
(cherry picked from commit 9958c0c4e9)
Turns `packages/core/e2e/e2e.test.ts` into a cross-language conformance
suite and adds `workbench/python` as its first non-JavaScript subject.
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Co-authored-by: Claude Opus 5 <noreply@anthropic.com>