Revert "disable code generation during freeze (#18875)" (#18882)

This reverts commit 4a169ab.

Author: diegomarquezp

.github/workflows/codegen.yaml

@@ -1,4 +1,7 @@
 on:
+  schedule:
+    # Runs at 12:30, 1:30 and 2:30.
+    - cron: '30 0-2 * * *'
   workflow_dispatch:
 
 name: codegen