Currently, we generate EVG tasks for multiple C++ driver versions that try to build the C++ libs against the C driver under test. The current task arrangement causes it to rebuild the C driver in full for each C++ repo version under test. This is unnecessary work that clogs up the CI system and makes everything slower than it needs to be.

Instead, we should just run the tests for all versions within the same EVG task that builds the C version that we want to test.