acp: Better telemetry IDs for ACP agents (#44544)

We were defining these in multiple places and also weren't leveraging
the ids the agents were already providing.

This should make sure we use them consistently and avoid issues in the
future.

Release Notes:

- N/A

crates/action_log/src/action_log.rs

@@ -777,7 +777,7 @@ impl ActionLog {
 
 #[derive(Clone)]
 pub struct ActionLogTelemetry {
-    pub agent_telemetry_id: &'static str,
+    pub agent_telemetry_id: SharedString,
     pub session_id: Arc<str>,
 }