Proposed commit message

The journald input from Filebeat requires the journalctl binary to ingest journal logs, this commit adds it by installing systemd in all Filebeat Docker container images

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

## Disruptive User Impact
## Author's Checklist

How to test this PR locally

1. Package Filebeat

   DEV=true SNAPSHOT=true PACKAGES="docker" PLATFORMS=linux/amd64 mage -v package

2. Ensure journalctl is present in the containers (adjust the image name/tag according to the version you built, oss or not)

   docker run --rm -it --user root --entrypoint "journalctl" docker.elastic.co/beats/filebeat-wolfi:9.1.0-SNAPSHOT --version
   docker run --rm -it --user root --entrypoint "journalctl" docker.elastic.co/beats/filebeat-ubi:9.1.0-SNAPSHOT --version
   # Only for x-pack
   docker run --rm -it --user root --entrypoint "journalctl" docker.elastic.co/beats/filebeat:9.1.0-SNAPSHOT --version

3. Start a stack. E.g: using elastic-package: elastic-package stack up --version=9.1.0-SNAPSHOT -v -d

4. Create the following filebeat.yml (adjust the IP address/ES host as needed)

   filebeat.yml

   filebeat.inputs:
     - type: journald
       id: foo-bar
       paths:
         - /var/log/journal/*/*.journal
   
   output.elasticsearch:
     hosts:
       - https://192.168.42.42:9200
     username: elastic
     password: changeme
     ssl.verification_mode: none

5. Then run Filebeat from the docker image (adjust the journald folder if needed)

   docker run --rm \
     --name=filebeat \
     --user=root \
     --volume="/var/log/journal:/var/log/journal:ro" \
     --volume="$(pwd)/filebeat.yml:/usr/share/filebeat/filebeat.yml:ro" \
     --volume="registry:/usr/share/filebeat/data:rw" \
     docker.elastic.co/beats/filebeat-wolfi:9.1.0-SNAPSHOT filebeat -e --strict.perms=false setup

6. Ensure there are no errors and data is ingested

Related issues

• Relates Add journalctl to Filebeat and Elastic-Agent docker images #44040
• Fixes [Filebeat] Journald input doesn't work in container #41278

## Use cases
## Screenshots
## Logs