CCM-10294: add ability to skip dynamic env plan

Author: mark-r-bjss

.github/workflows/dispatch_internal_repo_workflow.yaml

@@ -38,7 +38,7 @@ on:
       internalRef:
         type: string
         description: Internal repo reference (branch or tag)
-        default: "feature/CCM-10294_standardise-cicd-tests"
+        default: "main"
 
 permissions:
   id-token: write