Convert keylogging in response to comments

Convert keylogging in response to comments

1) Convert failures in keylog setup to trace messages for a warning-like
   mechanism

2) Convert sslkeylogfile_cb to be a flag used to determine making a
   direct call to the internal logging function

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Hugo Landau <hlandau@devever.net>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25297)