Max token capacity metric (#2595)

* adding max_token_capacity_metric

* added tgi to name of metric

* Adding max capacity metric.

* Add description for the metrics

---------
Co-authored-by: Edwinhr716 <Edandres249@gmail.com>

backends/v3/src/lib.rs

@@ -100,6 +100,7 @@ pub async fn connect_backend(
             .map_err(V3Error::Warmup)?,
     )?;
     tracing::info!("Setting max batch total tokens to {max_batch_total_tokens}");
+    metrics::gauge!("tgi_batch_max_total_tokens").set(max_batch_total_tokens);
 
     let backend_info = BackendInfo {
         waiting_served_ratio,

router/src/server.rs

@@ -1937,6 +1937,11 @@ async fn start(
         metrics::Unit::Count,
         "Maximum tokens for the current batch"
     );
+    metrics::describe_gauge!(
+        "tgi_batch_total_tokens",
+        metrics::Unit::Count,
+        "Maximum amount of tokens in total."
+    );
     metrics::describe_histogram!(
         "tgi_request_max_new_tokens",
         metrics::Unit::Count,