The uninitialized_fcv_jscore_passthrough suites pause initial sync at uninitialized FCV for the entire time. SERVER-86163 made transitionFromDedicatedConfigServer command in 8.0 do a w: all noop write. When initial sync is paused, this write is expected to time out waiting for write concern, causing these suites to not be able to start. So these suites are not compatible with the config shard build variant. Note we still have test coverage for initial sync with config shard in the concurrency_sharded_initial_sync suite.