Merge `ahm-tests` to `master` after AHM

[rockbmb]

Currently, the ahm-tests-update branch holds the changes to E2E tests required to run them in testnets' (Westend, Paseo) Asset Hubs.

After the AHM is performed in Kusama/Polkadot, this branch will need to be merged back to master of this repository, as some of the changes introduced by the migration will break tests (as they are in the main branch).

[rockbmb]

Done through #446 .