Another test race condition in the macos tests.
the test was waiting for PINGs to be generated and put on the replication stream,
but waiting for 1 or 2 seconds doesn't really guarantee that.
then the test that expected 6 full syncs, found only 4
these tests create several edge cases that are otherwise uncovered (at
least not consistently) by the test suite, so although they're no longer
testing what they were meant to test, it's still a good idea to keep
them in hope that they'll expose some issue in the future.
