chore: cleanup extraneous logging (#9156)

* The batchstats warning went out on every Ctrl+C in my development

Rule of silence:

The provisioner and connect messages messages were sent out on every startup
without a corresponding user event, making them annoying and more-so
debug messages.

coderd/batchstats/batcher.go

@@ -183,7 +183,7 @@ func (b *Batcher) run(ctx context.Context) {
 			// If the flush lever is depressed, flush the buffer immediately.
 			b.flush(authCtx, true, "reaching capacity")
 		case <-ctx.Done():
-			b.log.Warn(ctx, "context done, flushing before exit")
+			b.log.Debug(ctx, "context done, flushing before exit")
 			b.flush(authCtx, true, "exit")
 			return
 		}