Fail fast in image generation if not enough disk space for customers

[congyiwu]

Describe the bug
A clear and concise description of what the bug is, and why you consider it to be a bug.

If we promise X GB of free disk space for customers, we should check that there is enough space at the end of image generation, and fail fast if there isn't.

Area for Triage:

There wasn't an area for general stuff

Question, Bug, or Feature?:

Feature

Virtual environments affected

• macOS 10.15
• Ubuntu 16.04 LTS
• Ubuntu 18.04 LTS
• Windows Server 2016 R2
• Windows Server 2019

Expected behavior
A description of what you expected to happen.

There should always be at least X GB of free space.

Actual behavior
A description with steps to reproduce the issue. If your have a public example or repo to share,
please provide the link.

I don't think there are any safeguards besides customer's noticing and filing a bug.

[congyiwu]

potentially also fail fast or warn really loudly if we're getting close to X GB

[miketimofeev]

@congyiwu @nikita-bykov we shouldn't forget about additional 8Gb swap file on ubuntu, which is created later during VM provision

[congyiwu]

Also if we switch to the temp disk (via a bind mount, symlink, or changing the working for to /mnt), that would obviate this issue

[nikita-bykov]

We have added validation for available disk space.
Images with changes will be rolled out around next week.

[maxim-lobanov]

Closing the issue since test works as expected on all images