In BF-32157 we see the test fail and time out because we get unlucky and have a few very slow heartbeats to another node right around the time that we expect the node to select that one as a sync source.
This test already does an assert.soon to wait until the ping time of the old sync source is > 60 ms; we should add to that assert.soon to also wait until the ping time of the new sync source is < 60ms.