feat: docker improvements

[djerfy]

This PR include Docker improvements & fixes:

• Chia logs in the stdout if have CHIA_STDOUT variable declared (same as exporter)
• Use wallet mnemonic key into a secret by default (if file exist in the container, require docker swarm orchestrator)
• Switch to official chia-exporter (because retzkek have the last release 3 years ago)
• Improve chia-exporter build in a multi-stage
• Custom option target_peer_count with CHIA_PEER_COUNT variable
• Fix full_node_peers configuration

Docker image size from 1.4GB to 900MB