Remove `fetch(::Any)` method

[nalimilan]

fetch(::Any) is a no-op. It was imported from the Distributed stdlib by #30961. It's not clear why it's needed so we could consider removing it in Julia 2.0.

[vtjnash]

I think we could justify removing this on the grounds that it makes any overloading of fetch (e.g. in Distributed) is type-piracy (the method as documented now is required to return the argument unchanged :/ which isn't quite what it should be defined to do)