There is an undocumented 16KiB limit for text log messages.
However, the limit for JSON messages is 256KiB.
Even worse, logging JSON as text results in significant overhead
since each double quote needs to be escaped.
Instead, use logger.Logf.JSON to explicitly log the info as JSON.
We also modify osdiag to return the information as structured data
rather than implicitly have the package log on our behalf.
This gives more control to the caller on how to log.
Updates #7802
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
63b3c82587