fix: far_forward:collect:allow_failure:true since needs have allow_failure:truee

This should fix the failing collect stage when all needs have failed, e.g. https://eicweb.phy.anl.gov/EIC/benchmarks/reconstruction_benchmarks/-/jobs/1663692. If both needed jobs fail, there are no artifacts which include the required env.sh script provided by upstream.

benchmarks/far_forward/config.yml

@@ -29,4 +29,4 @@ far_forward:collect:
     - ["B0_far_forward_protons", "ZDC_far_forward"]
   script:
     - echo "Done collecting artifacts."
-
+  allow_failure: true