Remove RANDFILE settings from configuration files

Remove RANDFILE settings from configuration files

OpenSSL 1.1.1 introduced a new CSPRNG with an improved seeding
mechanism, which makes it dispensable to define a RANDFILE for
saving and restoring randomness. This commit removes the RANDFILE
declarations from our own configuration files and adds documentation
that this option is not needed anymore and retained mainly for
compatibility reasons.

Fixes #10433

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10436)