We used to always use nginx cert dir. When custom fallback certs
were set, we used to copy it in boxdata cert dir and then nginx cert dir.
The issue is then that we have to copy all certs to nginx cert dir on
cloudron restore.
To fix this, we simply give priority to nginx cert dir and not copy
around certs anymore. caas cert will reside in nginx cert dir and
not get backed up, as expected.
when certs change, we have to call into nginx anyway. since they
go hand in hand, just merge those files. modern reverse proxies
do this job integrated already.
