fix(playground): Use required root_hash options

[ryanschneider]

📝 Summary

As part of #429 the check was added to prevent start-up if the root_hash_use_sparse_trie and root_hash_compare_sparse_trie values weren't set correctly. This updates those values for the playground (I'm not sure if we want to update other config examples as well).

💡 Motivation and Context

Without this change cargo run --bin rbuilder run config-playground.toml (correctly) fails with:

Error: root_hash_use_sparse_trie=true and root_hash_compare_sparse_trie=false must be set, otherwise node will produce incorrect blocks or confusing error messages. These settings are enforced temporarily because upstream parallel root hash implementation is not correct.

Location:
    crates/rbuilder/src/live_builder/base_config.rs:303:13

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✅ I have completed the following steps:

• Run make lint
• Run make test
• Added tests (if applicable)