Docker - Test sync with different download policies

[pulpbot]

Author: kersom (kersom)

Redmine Issue: 4973, https://pulp.plan.io/issues/4973

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• Pulp 3 will offer different download policies, such as on_demand, streamed and immediate.
• Create tests for all those different scenarios.

We need to add a test covering streamed. The others already have tests in place

See: PullLazyContentTestCase

Besides that , add test that one can pull content from Pulp using streamed download policy.

[bmbouter]

We're going to look at enabling a variety of plugins individual tests, but to enable that we need a pytest marker change on pulp_container which can't be made here so I'm closing.