storage_helper.rb does not check available disk space

The test suite will currently try to create storage devices without checking whether the required disk space is available. Of course, test(s) will eventually fail but it would be preferable to fail much earlier in the process.

I’m currently testing a patch that addresses this.

Feature Branch: kytv:test/8907-check-space

Parent Task: #8539 (closed)

Original created by @kytv on 8907 (Redmine)