Address exposed internal classes

`platform-sdk/consensus-concurrent/src/main/java/module-info.java` exposes some internal packages. Either these classes are not internal or the external dependencies should be eliminated.

Start with platform-sdk/consensus-concurrent/src/main/java/module-info.java and inspect the exported packages and their external dependencies. Determine which packages are intended to be public and whether the referenced dependencies are required; done means the module no longer exposes unintended internal classes or retains unnecessary dependencies, with the module still compiling successfully.

Written by the indexing model from the issue text.