remove `sleep(Duration::from_secs(5));` from `deploy_devnet`

Currently when deploying a devnet, we sleep for 5 seconds to allow the bitcoin node to get initialized before starting the stacks node.

The chain coordinator should communicate with the API server to indicate that the bitcoin node is ready, and _then_ the subsequent nodes should be deployed.

Start at deploy_devnet and locate the fixed sleep after the bitcoin node is deployed. Trace how the chain coordinator and API server currently communicate, then determine how readiness should be signaled before subsequent nodes start. Done means deployment no longer relies on the five-second delay and waits for bitcoin readiness instead.

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