Cover container-split behavior in the Docker tests

[adamtheturtle]

tests/mock_vws/test_docker.py had one build-and-smoke test, so endpoints whose behavior depends on state crossing the container boundary — reco counts reports, VuMark instance generation, request rate limits and database deletion — had no real-topology coverage; the single-process backend cannot distinguish them (#3380).

The images are now built and the three containers run once per module, with the VWS container published on a known host port and VWS_BASE_URL pointed at it so report download URLs are reachable and survive a restart. On top of the existing add-target-and-query and Model Target restart tests, this adds one round trip per stateful feature: a reco counts report requested from VWS and downloaded from the URL it returns, VuMark instance generation from a target created in the target manager, a per-endpoint rate limit read from the target manager and enforced by VWS (and lost on VWS restart), and rejection of the keys of a deleted database.

pytestmark is added to vulture's ignore_names for the module-level requires_docker_build marker. All six tests pass locally, along with prek run --all-files, the manual hook stage and the partition check; the rename half of #3380 is deliberately not included.

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