database_attribute: Deliver/create index.txt.attr

database_attribute: Deliver/create index.txt.attr

Fixes #11904

Since OpenSSL-1.1.0x the database attribute file for IPSec and OpenVPN wasn´t created while initial PKI generation.
OpenVPN delivered an error message but IPSec did crashed within the first attempt.
This problem persists also after X509 deletion and new generation.

index.txt.attr will now be delivered by the system but also deleted and recreated while setting up a new x509.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>