Set JALIEN_USER so the tests need no GRID credential

This stops the workflow-creation tests from opening a JAliEn session.

- o2dpg_sim_workflow.py calls JAlien(['whoami']) only to fill the AOD
  --created-by field, and only when JALIEN_USER is unset.
- Setting it avoids putting a GRID certificate on a runner whose account also
  executes pull-request code.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: sawenzel

.github/workflows/sim-tests.yml

@@ -125,6 +125,12 @@ jobs:
           O2DPG_TEST_HASH_BASE: ${{ steps.base.outputs.sha }}
           O2DPG_TEST_HASH_HEAD: ${{ github.event.pull_request.head.sha }}
           JOBS: 8
+          # o2dpg_sim_workflow.py calls JAlien(['whoami']) purely to fill the
+          # AOD's --created-by field, and only when JALIEN_USER is unset. Setting
+          # it keeps the tests from needing a GRID credential at all, which
+          # matters here: anything readable by this account is readable by the
+          # fork-pull-request code that runs as it.
+          JALIEN_USER: alien-ci
         run: |
           set -eu
           # Everything after "-c" is joined into one string and re-evaluated