[PRMP-1567] Make the build_branch optional

Author: robg-test

.github/workflows/base-run-bulk-upload.yml

@@ -15,7 +15,7 @@ on:
         default: "ndr"
       build_branch:
         description: "Which Feature Branch for the Bulk Upload Script"
-        required: true
+        required: false
         type: "string"
         default: "main"
       environment: