fix(redhat): check usr/share/buildinfo/ dir to detect content sets

[DmitriyLewen]

Description

In RHCOS you don't have permissions to the /root directory.
That's why in RHCOS the content set files are in /usr/share/buildinfo/*.json

Related issues

• Close feat(redhat): also parse /usr/share/buildinfo for "content manifests" #8213

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
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• I've included a "before" and "after" example to the description (if the PR is a user interface change).