[8.17](backport #6470) [8.x] restore cloud defend as an expected binary

[mergify]

The cloud-defend binary was accidentally removed from 8.x starting with 8.17.0 in the backport for https://github.com/elastic/elastic-agent/pull/6042/files, likely as part of merge conflict resolution.

What does this PR do?

Includes the cloud-defend binary in the agent docker container again.

Why is it important?

Defend for containers which is implemented by cloud-defend is still a supported product in 8.x.

How to test this PR locally

DOCKER_VARIANTS=basic EXTERNAL=true SNAPSHOT=true PACKAGES=docker PLATFORMS=linux/arm64 mage package

docker run -it --entrypoint /bin/bash docker.elastic.co/beats/elastic-agent:8.18.0-SNAPSHOT
elastic-agent@240c9b878938:~$ ls data/elastic-agent-1f89c7/
components  elastic-agent  logs  otelcol  package.version
elastic-agent@240c9b878938:~$ ls data/elastic-agent-1f89c7/components/
LICENSE.txt                       bundle.tar.gz          lenses
NOTICE.pf-elastic-collector.txt   certs                  module
NOTICE.pf-elastic-symbolizer.txt  checksum.yml           osquery-extension.ext
NOTICE.pf-host-agent.txt          cloud-defend           osqueryd
NOTICE.txt                        cloud-defend.spec.yml  pf-elastic-collector

Related issues

• Closes Cloud Defend binary missing from 8.17.0+ containers #6469

  ---

  This is an automatic backport of pull request [8.x] restore cloud defend as an expected binary #6470 done by Mergify.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[cmacknz]

TestOtelAPMIngestion failure is unrelated, merging.