Skip subagents for gemini (#5257)

Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose/src/agents/agent.rs

@@ -1522,13 +1522,9 @@ impl Agent {
             self.extension_manager
                 .suggest_disable_extensions_prompt()
                 .await,
-            Some(model_name),
+            model_name,
             false,
         );
-        tracing::debug!(
-            "Built system prompt with {} characters",
-            system_prompt.len()
-        );
 
         let recipe_prompt = prompt_manager.get_recipe_prompt().await;
         let tools = self
@@ -1539,7 +1535,6 @@ impl Agent {
                 tracing::error!("Failed to get tools for recipe creation: {}", e);
                 e
             })?;
-        tracing::debug!("Retrieved {} tools for recipe creation", tools.len());
 
         messages.push(Message::user().with_text(recipe_prompt));
 
@@ -1754,7 +1749,7 @@ mod tests {
 
         let prompt_manager = agent.prompt_manager.lock().await;
         let system_prompt =
-            prompt_manager.build_system_prompt(vec![], None, Value::Null, None, false);
+            prompt_manager.build_system_prompt(vec![], None, Value::Null, "gpt-4o", false);
 
         let final_output_tool_ref = agent.final_output_tool.lock().await;
         let final_output_tool_system_prompt =