The integration test framework should test the DEB and RPM installations of the agent

[cmacknz]

• Relates [Fleet]: On enrolling RPM and Deb agents, Restarting agent failed error is displayed in CLI. #4084
• [upgrade] Deb package leaves stale symlink to elastic-agent #3784

At minimum we need to ensure that these packages install and can be enrolled in Fleet. The RPM and DEB tests should run in their own test group to ensure they run in parallel with other installation types.

The Fleet log ingestion test could be used for this purpose. https://github.com/elastic/elastic-agent/blob/main/testing/integration/logs_ingestion_test.go#L40

We should also test that they can be upgraded, see #3784. This will require dedicated test as this is a new upgrade path, this part of the work could be split into a separate issue if needed.

[elasticmachine]

Pinging @elastic/elastic-agent (Team:Elastic-Agent)

[pierrehilbert]

Reopening as only the DEB part has been done for now