it-tools is a copy of extensions-core/testing-tools (module name druid-testing-tools.)
The testing tools are added to the Druid test Docker image. The druid-testing-tools module defines most such additions. However, integration-tests defines a custom node role which also must be added to the image. integration-tests uses a different mechanism to do that addition.
Here, we want a single extension for all the testing gizmos. This is a direct copy of the druid-testing-tools extension, along with a copy of the custom node role from integration-tests.
The reason this is a copy, rather than fixing up druid-testing-tools is that the existing integration-tests must continue to run and it is very difficult to change or test them. (Which is the reason for this parallel approach.) To keep backward compatibility, and to avoid changing integration-tests, we keep the prior approach and make copies here for the new approach.
The names should never clash: it-tools is only ever used within the docker-test project, and the druid-testing-tools is not included as a dependency.
Over time, once integration-tests are converted, then the druid-testing-tools module can be deprecated in favor of this one.