remove simapp dependency for TestMsgStoreCodeGetSigners

[essenmeoikia]

Description

ref: #7771

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[gjermundgaraba]

Thanks for the PR :) The issue in question is a bigger refactor to not have a simapp in 08-wasm at all. I will close this PR for now as this will require some more thought and work in the future, which the team will take care of when we get there. Thank you :)

To avoid these issues in the future, I suggest asking in the issue itself if you can work on it, so we can help determine if it's a good contribute issue or not :)