validate_script: add retry for log publish check
validate_script: add retry for log publish check

There is a timing issue for publishing logs and checking that may
fail.  Make this check more robust by retrying.

Signed-off-by: Paul Barrette <b35f8c7746b911163b905ff32288e207dc9b1bbc@gmail.com>

rcwoolley/device-cloud-python,rcwoolley/device-cloud-python