ZTS: Annotate additonal flaky test cases

Update several flaky test cases in zts-report.py.in until they
can be made entirely reliable.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #14392