build: reduce batch size to try to reduce flakiness

Currently, we are getting a lot of flakes due to `accept4 failed 110` error, this commit tries to reduce this by reducing the batching

(cherry picked from commit 0371781)

Author: alan-agius4

scripts/windows-testing/convert-symlinks.mjs

@@ -133,7 +133,7 @@ try {
   // Re-link symlinks to work inside Windows.
   // This is done in batches to avoid flakiness due to WSL
   // See: https://github.com/microsoft/WSL/issues/8677.
-  const batchSize = 75;
+  const batchSize = 50;
   for (let i = 0; i < relinkFns.length; i += batchSize) {
     await Promise.all(relinkFns.slice(i, i + batchSize).map((fn) => fn()));
   }