gaia: baseline_floor off (feedback #1)

The floor gates a ship on a validation comparison while gaia's reward is on
the test partition (different distributions), so keep it opt-in / off. Now
that the harbor default is false this is explicit-for-clarity.

Author: varunursekar

harness-engineering-bench/gaia/baseline/build.yaml

@@ -38,7 +38,7 @@ objective:
     metric: score
   direction: maximize
 reward_mode: submit  # agent picks; falls back to auto_best, then current version
-baseline_floor: true
+baseline_floor: false  # gates on validation while reward is on test; opt-in only
 score_baseline: true
 rescore_top_k: 3
 rescore_attempts: 1