The unit-test task is currently configured on lots of WiredTiger Evergreen builders (build variants). There are also a few variants of the task e.g. unit-test-bucketxx, unit-test-long. that are configured at various testing stages (e.g. PR testing, merge testing) that have coverage overlap with the unit-test task. 

A recent audit of test/evergreen.yml reveals some testing redundancy about unit-test that can be saved on a few Evergreen builders, specifically the ! Ubuntu 20.04 and RHEL 8.0 builders.