CI: container tests fail on the ubuntu-26.04 runners (Testcontainers 1.19.7 and Docker 29) #76

Since 9 Nov 2026 every job of build_test that starts a container fails, before any test of ours runs: dialect/db/mariadb, mssqlserver, mysql, oracle and jdbc/metadata (run 42570483667). The last runs on 31 Oct were green with the same poms.

java.lang.IllegalStateException: Could not find a valid Docker environment. Please see logs and check configuration
	at org.testcontainers.dockerclient.DockerClientProviderStrategy.lambda$getFirstValidStrategy$7(DockerClientProviderStrategy.java:277)

Cause. The jobs now run on the image ubuntu-26.04 with Docker 29. Docker 29 no longer accepts the API version that Testcontainers 1.19.7 asks for, so Testcontainers finds no usable Docker and every container test fails, or is skipped where it may run without Docker. The cwm repository hit the same failure and moved to Testcontainers 1.21.4 (eclipse-daanse/org.eclipse.daanse.cwm@97b545495).

Fix. Testcontainers 1.21.4 in the seven poms that use it (dialect/db/{hive,mariadb,mssqlserver,mysql,oracle,postgresql}, jdbc/metadata). 1.21.4 works with recent Docker engines and keeps the artifact names of 1.19, so only the versions change.

Locally with Podman nothing else changes: Testcontainers finds the Podman socket through DOCKER_HOST (the poms pass it on to the tests) or through ~/.testcontainers.properties:

docker.host=unix:///run/user/<uid>/podman/podman.sock
ryuk.disabled=true

The round-trip tests stay opt-in with -Dintegration.docker=true, on GitHub as well as locally.