bridge tests: send bridged assets from random parachain to bridged asset hub (#4870)

- Send bridged WNDs: Penpal Rococo -> AH Rococo -> AH Westend
- Send bridged ROCs: Penpal Westend -> AH Westend -> AH Rococo

The tests send both ROCs and WNDs, for each direction the native asset
is only used to pay for the transport fees on the local AssetHub, and
are not sent over the bridge.

Including the native asset won't be necessary anymore once we get #4375.

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Signed-off-by: Adrian Catangiu <[email protected]>
Co-authored-by: command-bot <>