[ci] Fix build scan annotations on Windows (#101990) (#102028)

(cherry picked from commit f20ae0e)

Author: brianseeders

build-tools-internal/src/main/groovy/elasticsearch.build-scan.gradle

@@ -142,18 +142,17 @@ buildScan {
           // Add a build annotation
           // See: https://buildkite.com/docs/agent/v3/cli-annotate
           def body = """<div class="mb3"><span class="p1 border rounded">${System.getenv('BUILDKITE_LABEL')}</span> :gradle: ${result.failure ? 'failed' : 'successful'} build: <a href="${scan.buildScanUri}"><code>gradle ${gradle.startParameter.taskNames.join(' ')}</code></a></div>"""
-          new ProcessBuilder(
+          def process = [
             'buildkite-agent',
             'annotate',
             '--context',
             result.failure ? 'gradle-build-scans-failed' : 'gradle-build-scans',
             '--append',
             '--style',
-            result.failure ? 'error' : 'info',
-            body
-          )
-            .start()
-            .waitFor()
+            result.failure ? 'error' : 'info'
+          ].execute()
+          process.withWriter { it.write(body) } // passing the body in as an argument has issues on Windows, so let's use stdin of the process instead
+          process.waitFor()
         }
       }
     } else {