ZTS: Add known exceptions

The following seven tests been observed to occasionally fail during
CI testing. This commit adds them to the list of known somewhat
flaky test cases.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #12023