Goal: 

When convert2rhel fails (returns exit code 1), there's a critical-level log message printed to stderr, detailing what went wrong. The goal is for the script to parse the stderr and pass the detailed error message to Insights to show it to the user.

Acceptance Criteria:

• the conversion script sends a critical-level log message emitted by convert2rhel to Insights so that Tasks can show it to the user as a conversion result message.