Tests are failing for the `Wait for the output file to be created, should contain HTTP pinging`

[v1v]

What

The test assertion for hearbeat contains "scheme":"http" is failing

This assertion was introduced a long time ago:

• https://github.com/elastic/beats-tester/blob/eb09f0d674b92d3a4e683ce93d87699107bdc6cc/roles/test-linux-binary/tasks/main.yml#L74-L78
• https://github.com/elastic/beats-tester/commit/0022c19c60589cadbe4014f6100993d9a9318660

Version

It uses the latest 8.0-SNAPSHOT version stored in gs://beats-ci-artifacts/snapshots/heartbeat

Log

Error
Timeout when waiting for search string "scheme":"http" in /tmp/output/heartbeat
Stacktrace
{
"changed": false, 
"elapsed": 5, 
"msg": "Timeout when waiting for search string \"scheme\":\"http\" in /tmp/output/heartbeat"
}

[2021-06-15T16:04:10.902Z] TASK [test-linux-binary : Wait for the output file to be created, should contain HTTP pinging] ***
[2021-06-15T16:04:16.070Z] fatal: [tester-awslinux]: FAILED! => {"changed": false, "elapsed": 5, "msg": "Timeout when waiting for search string \"scheme\":\"http\" in /tmp/output/heartbeat"}
[2021-06-15T16:04:16.070Z] fatal: [tester-centos7-64]: FAILED! => {"changed": false, "elapsed": 5, "msg": "Timeout when waiting for search string \"scheme\":\"http\" in /tmp/output/heartbeat"}
[2021-06-15T16:04:16.070Z] fatal: [tester-awslinux2]: FAILED! => {"changed": false, "elapsed": 5, "msg": "Timeout when waiting for search string \"scheme\":\"http\" in /tmp/output/heartbeat"}
[2021-06-15T16:04:16.070Z] fatal: [tester-centos8-64]: FAILED! => {"changed": false, "elapsed": 5, "msg": "Timeout when waiting for search string \"scheme\":\"http\" in /tmp/output/heartbeat"}

You can see the whole log output in -> https://beats-ci.elastic.co/blue/rest/organizations/jenkins/pipelines/Beats/pipelines/beats-tester-mbp/branches/master/runs/476/nodes/77/log/?start=0

How to reproduce it

$ GROUP=centos make run-group