While syncing transaction spec tests for CDRIVER-2936, I accidentally deleted opts.yml, which was introduced in 84d7dda. I realized that this file wasn't present in the upstream mongodb/specifications transaction tests.

Rather than lump custom libmongoc spec tests in with upstream tests, would it make sense to segregate these in their own directory? As upstream files are introduced, modified, and deleted, this would minimize that chance that libmongoc-specific tests are inadvertently affected by future syncs.