Add grpc unit test run, expand testing of VectorFactory

[jhamon]

Problem

There is a small number of unit tests that should only get run when grpc dependencies are installed. These were previously omitted from CI by mistake.

Solution

Add a step to run these grpc steps. Make it conditional on the use_grpc test matrix param.

Type of Change

• [x] Infrastructure change (CI configs, etc)
• [ ] Non-code change (docs, etc)
• [ ] None of the above: (explain here)

[ssmith-pc]

Thanks!