Reduce log count

[squirrelsc]

Those line will create a lot of lines in log, but it's worth to capture the errors in Python patterns. So please update the logic, copy_back the files, and then check them. It will reduce log, and the downloaded files can be used for troubleshooting.

https://github.com/microsoft/lisa/blob/035f1af3832616ad80de64c52eb22752314e6ec9/microsoft/testsuites/core/azure_image_standard.py#L247

https://github.com/microsoft/lisa/blob/035f1af3832616ad80de64c52eb22752314e6ec9/microsoft/testsuites/core/azure_image_standard.py#L754