firmware_loader: Remove most Debian-specific logging changes
Since the "bookworm" release, the Debian installer will normally automatically install firmware packages based on a mapping of device IDs to firmware. This makes our changes to firmware_loader logging less important. There are also cases where we warn about missing firmware that isn't actually needed, which would require further intrusive changes to fix.
The installer itself still relies on a log message to detect missing firmware in the installation environment, but it doesn't care about the log level.
So, remove the current patches:
- Revert "firmware_class: Refer to Debian wiki page when logging missing firmware"
- Revert "firmware: Remove redundant log messages from drivers"
- Revert "firmware_class: Log every success and failure against given device" (Closes: #857198, #966218)
And add back just the message for direct loading failure, now at "info" level:
- firmware_loader: Log direct loading failures as info for d-i
Closes: #1040738