Disable creation of local XC-20s & remove tests

[fgamundi]

What does it do?

Substrate local XC-20 assets have been deprecated in favor of EVM ERC20 XCM tokens. This is the first of multiple PRs to deprecate localAssets in Moonbeam.
Sets the ForceOrigin of LocalAsset config to Never and remove related tests.

What important points reviewers should know?

Even though local assets are meant to be registered through assetManager.registerLocalAsset, setting the localAssets config origin to never is enough to make that extrinsic fail, effectually disabling the creation of new local XC20s, as shown with a dev env:

Is there something left for follow-up PRs?

Existing local XC20s in Moonbeam are not actively used. After the assets has been destroyed (through governance), follow-up PRs should be made to remove the localAssets pallet from the runtime

[github-actions]

Coverage generated "Mon Oct 2 23:29:56 UTC 2023":
https://d3ifz9vhxc2wtb.cloudfront.net/pulls/2508/html/index.html

Master coverage: 87.39%
Pull coverage:

[fgamundi]

@librelois @Agusrodri thanks for the review!
I've removed all tests related to local assets, could you please rereview? The typescript tests that shows as modified really are that the file was replaced with another and Git takes it as a modification (like test-hrmp-...-5 was removed and test-hrmp-...-6 was renamed to 5)

[Agusrodri]

@fgamundi the changes applied to tests look good 👍