perf: avoid double signing (#804)

## 📝 Summary

Avoid double signing the request when builder is submitting only to
regular or only to optimistic relays.

## ✅ I have completed the following steps:

* [x] Run `make lint`
* [x] Run `make test`
* [ ] Added tests (if applicable)

Author: efbig

crates/rbuilder/src/live_builder/block_output/relay_submit.rs

@@ -141,8 +141,9 @@ async fn run_submit_to_relays_job(
 ) -> Option<BuiltBlockInfo> {
     let mut res = None;
 
-    let (regular_relays, optimistic_relays) =
-        relays.into_iter().partition(|relay| !relay.optimistic());
+    let (regular_relays, optimistic_relays) = relays
+        .into_iter()
+        .partition::<Vec<_>, _>(|relay| !relay.optimistic());
 
     let mut last_bid_hash = None;
     'submit: loop {
@@ -253,20 +254,25 @@ async fn run_submit_to_relays_job(
             &block.sealed_block,
         );
         let (regular_request, optimistic_request) = {
-            let regular = create_submit_block_request(
-                &config.signer,
-                &config.chain_spec,
-                &slot_data,
-                &block,
-                &execution_payload,
-            )
-            .inspect_err(|error| {
-                error!(parent: &submission_span, ?error, "Error creating regular submit block request");
-            })
-            .ok();
+            let mut regular = None;
+            if optimistic_config.is_none() || !regular_relays.is_empty() {
+                regular = create_submit_block_request(
+                    &config.signer,
+                    &config.chain_spec,
+                    &slot_data,
+                    &block,
+                    &execution_payload,
+                )
+                .inspect_err(|error| {
+                    error!(parent: &submission_span, ?error, "Error creating regular submit block request");
+                })
+                .ok();
+            }
 
             let mut optimistic = None;
-            if let Some(optimistic_config) = optimistic_config {
+            if let Some(optimistic_config) =
+                optimistic_config.filter(|_| !optimistic_relays.is_empty())
+            {
                 optimistic = create_submit_block_request(
                     &optimistic_config.signer,
                     &config.chain_spec,
@@ -283,7 +289,9 @@ async fn run_submit_to_relays_job(
         };
 
         if regular_request.is_none() && optimistic_request.is_none() {
-            error!(parent: &submission_span, "Unable to construct request from the built block");
+            let regular_relays_len = regular_relays.len();
+            let optimistic_relays_len = optimistic_relays.len();
+            error!(parent: &submission_span, regular_relays_len, optimistic_relays_len, "Unable to construct request from the built block");
             continue 'submit;
         }