Fix syntax for slack notification

See gh-22709

ci/pipeline.yml

@@ -55,7 +55,7 @@ anchors:
         "zip.type": "docs"
         "zip.deployed": "false"
   slack-fail-params: &slack-fail-params
-    text: ":concourse-failed: @here <https://ci.spring.io/teams/${BUILD_TEAM_NAME}/pipelines/${BUILD_PIPELINE_NAME}/jobs/${BUILD_JOB_NAME}/builds/${BUILD_NAME}|${BUILD_PIPELINE_NAME} ${BUILD_JOB_NAME} failed!>"
+    text: ":concourse-failed: <!here> <https://ci.spring.io/teams/${BUILD_TEAM_NAME}/pipelines/${BUILD_PIPELINE_NAME}/jobs/${BUILD_JOB_NAME}/builds/${BUILD_NAME}|${BUILD_PIPELINE_NAME} ${BUILD_JOB_NAME} failed!>"
     silent: true
     icon_emoji: ":concourse:"
     username: concourse-ci