revert buildkite_analytics_token deletion

Author: pazone

.buildkite/bk.integration.pipeline.yml

@@ -495,7 +495,10 @@ steps:
     soft_fail:
       - exit_status: "*"
     plugins:
-      - *vault_ec_key
+      - elastic/vault-secrets#v0.1.0:
+          path: "kv/ci-shared/platform-ingest/buildkite_analytics_token"
+          field: "token"
+          env_var: "BUILDKITE_ANALYTICS_TOKEN"
       - test-collector#v1.11.0:
           files: "build/*.xml"
           format: "junit"