Iostats fix

[shmish111]

Note: Please remember to review the Datadog Contribution Guidelines if you have not yet done so.

What does this PR do?

Parse iostats correctly on nixos

Motivation

iostats not being parsed correctly on nixos

Testing Guidelines

An overview on testing is available in our contribution guidelines.

Additional Notes

This will probably break other linux distributions, it is just a demo of what is wrong, probably needs to be fixed by more detailed parsing.