tests: Lift requirement on java/dotnet on the host tester

For `dotnet_command_line` and `java_command_line` we require `dotnet` and `java` respectively to be installed on the host.

Instead of requiring them - we should copy the artifacts from the build application containers. The host tester should not require dotnet/java, or rather, should require them only for the tests that truly use them and not as a fixture that's always called. (alternatively we can make this fixture lazy)