refactor(bench): remove completion messages in normal mode for cleaner output

Removed the '✓ Completed: {template_name}' message that appeared after
each benchmark in normal (non-quiet) mode.

Before: Progress bar -> ✓ Completed: Split all -> Template results
After:  Progress bar -> (cleared) -> Template results

This makes the output cleaner and less verbose while still showing
progress bars during execution. The --quiet mode still shows the
completion messages for minimal output tracking.

Author: claude

src/bin/bench_throughput.rs

@@ -826,11 +826,7 @@ fn main() {
                     let _ = execute!(
                         stdout,
                         cursor::MoveToColumn(0),
-                        Clear(ClearType::CurrentLine),
-                        SetForegroundColor(Color::Green),
-                        Print("✓ "),
-                        ResetColor,
-                        Print(format!("Completed: {}\n", template_name))
+                        Clear(ClearType::CurrentLine)
                     );
                     print_template_results(template_name, &results);
                 } else {