test: support deploy exclusions with force gates (#98149)
## Summary
- add static gate conditions for the deployment CI variants used by
existing test suites
- support `@force-gate` on parameterized `describe.each` suites
- document and test the force-gate infrastructure needed by the
migration
This establishes the gate support used by the deployment-exclusion
migration PRs above it.
## Verification
- `pnpm typescript`
- `pnpm jest test/unit/gate/pragma-transform.test.ts
test/unit/gate/runtime.test.ts --runInBand`
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