Update docker image to Ubuntu 20.04

[simitt]

Update to latest libbeat version for changing the docker base image from CentOS to Ubuntu 20.04 (elastic/beats#29681)

Pulling in latest libbeat will also add other changes, highlighting the ones relevant for APM:

• Update golang version to 1.17.5
• Add Elastic Product origin header (Add the Elastic product origin header when talking to Elasticsearch or Kibana. beats#29966)
• Support self signed certs on output (Support self-signed certificate on outputs beats#29229)
• Change logs from json to ndjson (Remove logging.files.suffix option and always use datetime suffixes beats#28927) and file suffix (Remove logging.files.suffix option and always use datetime suffixes beats#28927)

[axw]

Closed by #7137