bf.cfg files are limited to 16 KB in size and if they are larger bfb-install fails silently

[lgarbarini]

Wanted to post this in case others get tripped up and in the hope that the BSP docs are updated:

We can end up producing decently large bf.cfg files on the fly to do customization. Most of this involves injecting cloud-init mime-multipart user-data for things like systemd units/config files. This means that occasionally our bf.cfg files exceeded 16 KB which resulted in sporadically failing deployments.

This limit appears to be only documented in the code here: https://github.com/Mellanox/bfb-build/blob/8132268837c382a8f167b4877c33b87609116128/ubuntu/22.04/install.env/common#L615-L619

It would be great if the BSP docs covered this and/or bfb-install warned that this will likely fail.

EDIT: also cross-filed as nvidia bug 4704764