fix(bk): serverless-beats-tests start failing after merging elastic#10734

Author: v1v

.buildkite/serverless.beats.tests.yml

@@ -1,8 +1,4 @@
 # yaml-language-server: $schema=https://raw.githubusercontent.com/buildkite/pipeline-schema/main/schema.json
-
-env:
-  VAULT_PATH: "kv/ci-shared/observability-ingest/cloud/gcp"
-
 steps:
   - label: "Serverless Beats Tests"
     key: "serverless-beats-integration-tests"
@@ -14,3 +10,10 @@ steps:
     agents:
       provider: "gcp"
       machineType: "n2-standard-8"
+    plugins:
+      # See https://github.com/elastic/oblt-infra/blob/main/conf/resources/repos/elastic-agent/01-gcp-oidc.tf
+      # This plugin authenticates to Google Cloud using the OIDC token.
+      elastic/oblt-google-auth#v1.3.0:
+        lifetime: 10800 # seconds
+        project-id: "elastic-observability-ci"
+        project-number: "911195782929"