XCMv5: Fix for compatibility with V4 (#6503)

## Description

Our smoke tests transfer `WETH` from Sepolia to Westend-AssetHub breaks,
try to reregister `WETH` on AH but fails as following:


https://bridgehub-westend.subscan.io/xcm_message/westend-4796d6b3600aca32ef63b9953acf6a456cfd2fbe

https://assethub-westend.subscan.io/extrinsic/9731267-0?event=9731267-2

The reason is that the transact call encoded on BH to register the asset

https://github.com/paritytech/polkadot-sdk/blob/a77940ba

/bridges/snowbridge/primitives/router/src/inbound/mod.rs#L282-L289
```
0x3500020209079edaa8020300fff9976782d46cc05630d1f6ebab18b2324d6b1400ce796ae65569a670d0c1cc1ac12515a3ce21b5fbf729d63d7b289baad070139d01000000000000000000000000000000
```

the `asset_id` which is the xcm location can't be decoded on AH in V5

Issue initial post in
https://matrix.to/#/!qUtSTcfMJzBdPmpFKa:parity.io/$RNMAxIIOKGtBAqkgwiFuQf4eNaYpmOK-Pfw4d6vv1aU?via=parity.io&via=matrix.org&via=web3.foundation

---------

Co-authored-by: Adrian Catangiu <[email protected]>
Co-authored-by: Francisco Aguirre <[email protected]>