chore: Revert throughput reporting feature from progress tracker

The Rich progress bar has complexities with live mode that make it difficult
to get visual feedback working correctly. Since the migration is running well
and fast (~18-20k rows/sec), the progress bar visual feedback is nice-to-have
but not essential. Focus on what matters: the migration completing correctly.

The existing TransferSpeedColumn (Kb/s) still provides throughput feedback
which is the most important metric.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/utils/progress.py

@@ -67,17 +67,6 @@ class ProgressTracker:
             self.progress.update(self.task_id, advance=advance)
             self.processed += advance
 
-            # For very large totals (e.g., migrations), show throughput periodically
-            # to give visual feedback even when progress percentage seems stuck
-            if self.processed % 1000000 == 0 and self.processed > 0:
-                elapsed = time.time() - self.start_time
-                if elapsed > 0:
-                    rate = self.processed / elapsed
-                    self.print_status(
-                        f"[cyan]Progress: {self.processed:,}/{self.total:,} items "
-                        f"({rate:.0f} items/sec, {elapsed/3600:.1f}h elapsed)[/cyan]"
-                    )
-
     def print_status(self, message: str):
         """Print a status message without interrupting progress bar."""
         if self.task_id is not None: