The resharding test fixture adds shards after setting up its ShardingTest, and in the CSRS stepdown suite, the stepdown thread begins after ShardingTest is constructed, so a stepdown can interrupt the addShard and rarely lead to failures finding a primary if the failover and detection of the new primary is slow enough. Resharding tests are disabled in this suite via a regex, but the internal transactions resharding tests are in a subdirectory and don't match it. There's no extra coverage from running these tests in this suite, so we should disable them to avoid failures.