[pytest] Docker images are always pulled, also when not missing.

[Jelmerdw]

Description

In our conftest.py, we use docker compose -f {COMPOSE_FILE} pull --policy missing to pull missing images for the test. However, the images are also pulled when they are locally build already. This takes unnecessary time and means that the local image is not used, which is desired when local changes are made.

Steps to Reproduce

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2. Run '...'
3. Observe '...'

Expected Behavior

What you expected to happen instead.

Additional Context

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