fix(builder-playground): config-playground.toml tweaks for playground DX

[ryanschneider]

📝 Summary

While getting flashbots/builder-playground#37 working I ran into a couple DX gotchas with the current config-playground.toml file.

💡 Motivation and Context

• The parallel algoirthm was pegging all my CPUs at 100%. Also figured just running mgp-ordering is enough.
• Having a random coinbase made it harder to test block building since we only build profitable blocks. IIRC we now have a setting to build always, but I still think it's cleaner to use the prefunded accounts from the playground.
• Having debug logs helped a ton tracking down pectra issues, so I expect it's useful any time anyone is using the playground for development.

---

✅ I have completed the following steps:

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

[github-actions]

Benchmark results for 76fe5ee

Report: https://flashbots-rbuilder-ci-stats.s3.us-east-2.amazonaws.com/benchmark/76fe5ee-cf49d29/report/index.html

Date (UTC)	2025-01-20T23:05:24+00:00
Commit	76fe5eed81774b7e7d49ef3526cbe44aaa52f1cd
Base SHA	cf49d292aa559f9405bf37963f206b7aaa809a6c

Significant changes

Benchmark	Mean	Status
ptr_trie_insert_only_3000	-2.61%	Performance has improved.
hashing_3000_elements_with_cache	3.04%	Performance has degraded.
cloning_3000_branch_node_size_elements	3.56%	Performance has degraded.
gather_nodes_clone	-11.78%	Performance has improved.
gather_nodes_empty_account	-24.12%	Performance has improved.