[ci] Fix Jenkinsfile to use the json files for pipeline benchmarks reporting (#8346)

* Fix Jenkinsfile to use the json files for pipeline benchmarks reporting

* Change extension in stashBenchmarkResults

Author: marc-gr

.ci/Jenkinsfile

@@ -194,14 +194,14 @@ def gitHubCommentWithBenchmarkReport() {
     }
     dir("${BASE_DIR}") {
       // download artifacts for this PR
-      def bucketUri = getBenchmarkBucketURI() + "*.xml"
+      def bucketUri = getBenchmarkBucketURI() + "*.json"
       log(level: 'INFO', text: "googleStorageDownload(bucketUri: ${bucketUri}, localDirectory: ${currentBenchmarkResults}, pathPrefix: ${getBenchmarkPathPrefix()})")
       googleStorageDownload(bucketUri: bucketUri, credentialsId: "${JOB_GCS_CREDENTIALS}", localDirectory: currentBenchmarkResults, pathPrefix: getBenchmarkPathPrefix())
 
       // download artifacts from the target branch if any
       if (env.CHANGE_TARGET) {
         try {
-          copyArtifacts(filter: "${currentBenchmarkResults}/*.xml", flatten: true, optional: true, projectName: getBaselineJobName(), selector: lastWithArtifacts(), target: baseline)
+          copyArtifacts(filter: "${currentBenchmarkResults}/*.json", flatten: true, optional: true, projectName: getBaselineJobName(), selector: lastWithArtifacts(), target: baseline)
         } catch(e) {
           log(level: 'INFO', text: 'gitHubCommentWithBenchmarkReport: it was not possible to copy the previous build.')
           return
@@ -398,7 +398,7 @@ def prepareStack() {
 }
 
 def stashBenchmarkResults() {
-  def wildcard = 'build/benchmark-results/*.xml'
+  def wildcard = 'build/benchmark-results/*.json'
   r = sh(label: "isBenchmarkResultsPresent", script: "ls ${wildcard}", returnStatus: true)
   if (r != 0) {
     echo "isBenchmarkResultsPresent: benchmark files not found, report won't be stashed"