test: use bootstrapped Tempo localnet

[brendanjryan]

Motivation

The Python SDK integration suite should use Tempo’s canonical deterministic faucet setup instead of maintaining raw node flags and a private-key funding fallback.

Summary

• replace the hand-configured Tempo node with the digest-pinned localnet image
• simplify account funding around the canonical localnet faucet
• remove redundant CI image caching and node setup

Key design considerations

• keep Redis and Tempo readiness coordinated through Docker Compose
• preserve TEMPO_LOCALNET_IMAGE overrides and use a 1 ms block interval for reliable bootstrap