Coverage: Integration tests for tree distribution

[btcookies]

We have an e2e integration test, but we should add in tests that check tree balances before and after and assert that they're increasing how we expect them to. This is especially important for custom handling addresses like badger tree and ibbtc peaks where if rewards are incorrectly distributed it will be at users' expense.

• sanity check new_token_totals = old_token_totals + expected_token_distribution
• balance_ibbtc_peak_after == before
• test for badger tree custom handler

[mitche50]

Wouldn't the second check be balance_ibbtc_msig == before_balance_ibbtc_peak + before_balance_ibbtc_msig?