This comment suggests that all drivers should test against these server versions:

• Supported major releases (for Go: 2.6, 3.0, 3.4, 3.6, 4.0, 4.2, 4.4, 5.0)
• The latest build from evergreen (e.g. 5.3.0-alpha...)
• The latest rapid release (currently 5.2 only, not 5.1).

We can now specify the "rapid" version in Evergreen test configs, which uses the most recent rapid server release version (currently v5.2). Add the "rapid" version to all test variants that currently test on "latest".