bk: update junit-annotate to run faster (#357)

Author: Copilot

.buildkite/pipeline.yml

@@ -71,12 +71,14 @@ steps:
       - "junit-*.xml"
 
   - label: ":junit: Junit annotate"
+    agents:
+      # requires at least "bash", "curl" and "git"
+      image: "docker.elastic.co/ci-agent-images/buildkite-junit-annotate:1.0"
     plugins:
-      - junit-annotate#v2.4.1:
+      - junit-annotate#v2.7.0:
           artifacts: "junit-*.xml"
           fail-build-on-error: true
-    agents:
-      provider: "gcp" #junit plugin requires docker
+          run-in-docker: false
     depends_on:
       - step: "test-lin"
         allow_failure: true