Remove wasm grandpa tests and introduce wasm tendermint tests

[srdtrk]

Summary

Grandpa wasm tests were disabled due them failing after changes in the 08-wasm module. We found it difficult to keep the grandpa contract and related docker images up to date. Instead, we should introduce tests for wasm 07-tendermint from ibc-rs.

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[srdtrk]

I've opened an issue and PR to update contract APIs of ibc-rs. cosmos/ibc-rs#1277