security: add curl timeouts to prevent script hanging

[DeVikingMark]

Add connection and maximum timeouts to curl commands in op-node-entrypoint

• Add --max-time 10 and --connect-timeout 5 to curl in get_public_ip()
• Add same timeouts to curl in execution client readiness check
• Prevents script hanging when external IP services are slow/unavailable
• Improves reliability and security of node startup process

[cb-heimdall]

✅ Heimdall Review Status

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