Add julia load and depot paths

Author: petebachant

.buildkite/perf/pipeline.yml

@@ -5,6 +5,8 @@ agents:
   modules: climacommon/2025_05_15
 
 env:
+  JULIA_LOAD_PATH: "${JULIA_LOAD_PATH}:${BUILDKITE_BUILD_CHECKOUT_PATH}/.buildkite"
+  JULIA_DEPOT_PATH: "${BUILDKITE_BUILD_PATH}/${BUILDKITE_PIPELINE_SLUG}/depot/default"
   JULIA_MAX_NUM_PRECOMPILE_FILES: 100
   GKSwstype: 100
   SLURM_KILL_BAD_EXIT: 1