Fix clippy::println_empty_string, clippy::while_let_on_iterator, clippy::while_let_on_iterator lint style violations (#36613)

Related: #36577

Release Notes:

- N/A

crates/eval/src/eval.rs

@@ -706,7 +706,7 @@ fn print_report(
             println!("Average thread score: {average_thread_score}%");
         }
 
-        println!("");
+        println!();
 
         print_h2("CUMULATIVE TOOL METRICS");
         println!("{}", cumulative_tool_metrics);

crates/eval/src/instance.rs

@@ -913,9 +913,9 @@ impl RequestMarkdown {
             for tool in &request.tools {
                 write!(&mut tools, "# {}\n\n", tool.name).unwrap();
                 write!(&mut tools, "{}\n\n", tool.description).unwrap();
-                write!(
+                writeln!(
                     &mut tools,
-                    "{}\n",
+                    "{}",
                     MarkdownCodeBlock {
                         tag: "json",
                         text: &format!("{:#}", tool.input_schema)