boot-config-loader: T1622: add missing groups to failsafe user
This extends commit 86d1291ec5 ("[boot-config-loader] T1622: Add failsafe
and back trace") and adds missing groups to the vyos user. Without this
change the vyos user will only have operator (vyos@vyos>) privileges,
even if this level is discontinued.
One could hack himself up as the user has sudo rights, but rather place
the user in the right groups from the beginning.
NOTE: This user is only added if booted with "vyos-config-debug" and
an error when the configuration can not be loaded at all.