refactor(frontend): remove fallback from ic-token derived stores

[AntonioVentilii-DFINITY]

Motivation

The derived store tokenWithFallback falls back on ETH (or SepoliaETH) and consequently even the store tokenWithFallbackAsIcToken.

However, it is unnecessary for the derived stores that checks if a particular token is a ck-token, since ETH will never have a prop ledgerCanisterId (and the util functions checks for a non-nullish token).

So we remove that particular usage from the code substituting tokenWithFallbackAsIcToken with tokenAsIcToken.

[peterpeterparker]

Are you sure it works in every use case and feature of the dApp? Have you thoroughly tested this? tokenAsIcToken is actually cast as IcToken, but after reviewing the code, it seems to be a shorthand, as it can actually be null or undefined.

On another note, could you first provide a test in a separate PR for the existing derived stores modified in this PR? It would be great to start testing those stores, given that this information is highly sensitive. WDYT?

[AntonioVentilii-DFINITY]

On another note, could you first provide a test in a separate PR for the existing derived stores modified in this PR?

You mean the utils inside the stores? Or the whole logic of the derived stores?

[peterpeterparker]

Or the whole logic of the derived stores?

I meant the all logic - like starting testing derived stores