Use Testcontainers instead of custom CrateDB integration test helper

Hi there,

the [BaseIntegrationTest.java] currently uses `io.crate.testing.CrateTestCluster` and `io.crate.testing.CrateTestServer` from [CrateDB Java Testing Classes]. If it is capable enough to replace this layer, we could now use [Testcontainers for Java » CrateDB support], thanks to @matriv's contribution https://github.com/testcontainers/testcontainers-java/pull/6790, which has been released yesterday.

With kind regards,
Andreas.

[BaseIntegrationTest.java]: https://github.com/crate/crate-jdbc/blob/master/driver/test/java/io/crate/client/jdbc/integrationtests/BaseIntegrationTest.java
[CrateDB Java Testing Classes]: https://github.com/crate/crate-java-testing
[Testcontainers for Java » CrateDB support]: https://www.testcontainers.org/modules/databases/cratedb/

Start with test/java/io/crate/client/jdbc/integrationtests/BaseIntegrationTest.java and compare its use of CrateTestCluster and CrateTestServer with the linked Testcontainers for Java CrateDB support. Verify whether the replacement covers the current integration-test needs, then run the integration tests; done means the custom helper is no longer required and the tests pass.

Written by the indexing model from the issue text.