Slow unit tests

When we run our unit tests from within Rider, they take a very long time to complete. It appears that the individual tests are fast but there are long pauses between them, in the order of tens of seconds.

When we start the same set of unit tests from within the Unity editor, they finish nearly instantly.

When we run tests in our non-Unity projects from within Rider, they also run normally.

So the problem appears to be in how resharper-unity launches the tests.

Reproduce the slowdown by running the same unit-test set from Rider and the Unity editor, then compare the test-launch behavior with non-Unity projects in Rider. Trace the resharper-unity test-launch path; done means the long pauses between individual tests are eliminated while the tests still run successfully.

Written by the indexing model from the issue text.