Freeze utils_test/libvirt.py

[dzhengfy]

@sathnaga @balamuruhans @smitterl ,

Here we have a new plan for virttest/utils_test/libvirt.py.
As this file is becoming bigger and bigger, there are too many kinds of functions mixed up in this file. The readability and usability is also getting worse and worse. So we plan to lock down this file that no more new functions are allowed to be added into it. And at same time, we plan to create a new folder named with virttest/utils_libvirt, and will create multiple files under utils_libvirt/ by feature on demand, such as memory, cpu, migration and so on. Those files are used to contain the utility functions which are mostly virsh commands related.

So welcome your comments. And if no objection, please help avoid of new functions in libvirt.py any more.
Thanks a lot.

[smitterl]

@dzhengfy Sounds good 👍

[sathnaga]

@dzhengfy sounds grt,