Create test for returning non-empty app_hash from InitChain

[amaury1093]

Summary

Create a meaningful test for returning app_hash from InitChain after an upgrade

Problem Definition

After #7020 & #7208, InitChain returns the app_hash to Tendermint.

For a fresh chain, the app_hash is sha256(""). This use case is tested.
For an upgrade, app_hash is the last commitID. This use case is not tested.

Proposal

Add a test case (ideally an integration test) that would look like:

• launch a chain
• wait a couple of blocks
• stop the chain, do an upgrade
• run the upgraded chain (with same store)
• expected: the upgraded chain should call InitChain, and return the last commitID of the store.

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
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[tac0turtle]

closing this as it will be done in v2