fix script location

Author: idegtiarenko

.buildkite/pipelines/periodic-micro-benchmarks.yml

@@ -2,7 +2,7 @@ steps:
   - label: periodic-micro-benchmarks
     command: |
       .ci/scripts/run-gradle.sh :benchmarks:run --args 'org.elasticsearch.benchmark._nightly -rf json -rff build/result.json'
-      .ci/scripts/index-micro-benchmark-results.sh
+      .buildkite/scripts/index-micro-benchmark-results.sh
     env:
       USE_PERF_CREDENTIALS: "true"
     timeout_in_minutes: 300