light-node: Re-enable test commented out because of cargo bug surfaced in WASM PR

[romac]

In the WASM PR (#553), I had to disable the only previously enabled acceptance test of the light node CLI for the test suite to pass (7c07134).

Without this commit, cargo test --all-features --no-fail-fast would fail with:

       Doc-tests tendermint-light-client
    error[E0460]: found possibly newer version of crate `tendermint` which `tendermint_rpc` depends on
     --> /Users/coromac/Informal/Code/Current/tendermint-rs/light-client/src/components/io.rs:7:5
      |
    7 | use tendermint_rpc as rpc;
      |     ^^^^^^^^^^^^^^
      |
      = note: perhaps that crate needs to be recompiled?
      = note: the following crate versions were found:
              crate `tendermint`: /Users/coromac/Informal/Code/Current/tendermint-rs/target/debug/deps/libtendermint.rlib
              crate `tendermint`: /Users/coromac/Informal/Code/Current/tendermint-rs/target/debug/deps/libtendermint-735716e8d731096d.rmeta
              crate `tendermint_rpc`: /Users/coromac/Informal/Code/Current/tendermint-rs/target/debug/deps/libtendermint_rpc-ad41c355acf2752f.rlib

    error: aborting due to previous error

It is currently unclear why this error has appeared, though I suspect it is a bug in Cargo related to features flags (which we now use to disable non WASM-compatible code).

The likely reason for why disabling this test resolves the issue above, is that there is no more a need to rebuild the light node crate to run the light node binary with cargo run. It's not clear why rebuilding the crate is necessary when running cargo run as part of the test (when everything should have been compiled already, though perhaps not with the same flags) but I suspect that doing so in the middle of running (doc)tests is causing the issue.

[thanethomson]

Seems like this may no longer be relevant?