nit: diff minimisation between asset hub runtimes (#2951)

* diff minimisation between runtimes

* another nit

* Update parachains/runtimes/assets/asset-hub-westend/src/xcm_config.rs

Co-authored-by: joe petrowski <[email protected]>

* Update parachains/runtimes/assets/asset-hub-polkadot/src/xcm_config.rs

Co-authored-by: joe petrowski <[email protected]>

* Upgrade english

* Removed unused `CheckedExtrinsic` (#2972)

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Co-authored-by: joe petrowski <[email protected]>
Co-authored-by: Branislav Kontur <[email protected]>