Summary

Add end-to-end test coverage for the new deferred dispatch flow in pallet-whitelist,
once paritytech/polkadot-sdk#11336 is merged.

Background

RFC #11199 proposes extending pallet-whitelist so that a whitelisted call can be
scheduled to dispatch after a delay, rather than executed immediately by
DispatchWhitelistedOrigin. The implementation in #11336 adds:

• A deferred-dispatch storage entry keyed by call_hash.
• A permissionless executor path: any account may trigger the deferred call once
  its delay has elapsed (event: DeferredDispatchExecuted { call_hash, who }).
• Permissionless removal of expired/cancelled deferred dispatches.
• Runtime wiring in asset-hub-westend (governance/mod.rs) as the first integration target.
• Benchmarks for the new extrinsics.

Unit tests exist in the pallet, but we need runtime-level e2e tests.

Scope

E2E tests should cover, at minimum:

• Happy path — DispatchWhitelistedOrigin schedules a deferred dispatch;
  after the delay, a permissionless account executes it; assert
  DeferredDispatchExecuted { call_hash, who } is emitted with the executor's account.
• Early execution rejected — attempting to dispatch before the delay elapses fails.
• Root-origin dispatch semantics — confirm the deferred call is dispatched as
  Root (matches lib.rs:228); a whitelisted call requiring Signed origin should
  surface BadOrigin end-to-end, and the test should pin this behavior so any future
  change is intentional.
• Permissionless removal — anyone can clean up a deferred entry once it is eligible
  for removal; storage is cleared and weight is refunded as expected.
• Origin gating on scheduling — only DispatchWhitelistedOrigin can create a
  deferred dispatch; other origins fail.
• Preimage interaction — missing/unavailable preimage at execution time yields
  UnavailablePreImage; restoring the preimage allows execution.

Blocked by

• pallet-whitelist: Deferred Dispatch paritytech/polkadot-sdk#11336