Strip colons from all test result filenames

The upload artifact functionality in github can't handle colons in
filenames. The current code handles this for files under the most
recent set of results. With the ability to rerun failed tests, now
there can be multiple sets of results, and they all need to be
processed in the same way.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: John Kennedy <john.kennedy@delphix.com>
Closes #12815