Correctly handle max_depth in tree solver

[EgorKraevTransferwise]

Context

Fix the way tree solver handles max_depth; align interpretation with rest of package and make sure it's actually enforced

Checklist

• Change meets or does not compromise the Baseline Security Requirements

[wise-github-bot-app]

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Your CODEOWNERS file is broken, fix the following errors before merging the branch:

• The CODEOWNERS file does not exist. Repository ownership will default to ENGINEERING until you add a CODEOWNERS file with a * rule that assigns it to a team

[wise-github-bot-app]

The approval(s) from AlxdrPolyakov do(es)n't fullfill the approvers requirements because:

• The approver's cost centre, PRDANA, maps to the ANALYST business function. As the code that was changed is owned by ENGINEERING, this approval won't satisfy our separation of duties check. We'll need an additional approval from someone in ENGINEERING. This approval may still help satisfy other codeowner requirements.