acp: Remove ACP v0 (#36785)

We had a few people confused about why some features weren't working due
to the fallback logic.

It's gone.

Release Notes:

- N/A

crates/agent_servers/Cargo.toml

@@ -22,7 +22,6 @@ acp_thread.workspace = true
 action_log.workspace = true
 agent-client-protocol.workspace = true
 agent_settings.workspace = true
-agentic-coding-protocol.workspace = true
 anyhow.workspace = true
 client = { workspace = true, optional = true }
 collections.workspace = true