Change:
- On CentOS Stream, make distribution_release be "Stream"
- On CentOS Core, it continues to be "Core"
- Implement custom distribution file parser for CentOS, so we can look
for "CentOS Linux" and "CentOS Stream"
- Two new fixtures introduced (CentOS Linux 8.1 and CentOS Stream 8)
- Removed two dicts from `Distribution` class that were seemingly not
used anywhere.
Test Plan:
- ci_complete
- New test fixtures
Tickets:
- Fixes#73027
Signed-off-by: Rick Elrod <rick@elrod.me>