Remove debug error_log level from default F5 WAF for NGINX conf examples

[ald8]

It is probably better to not set the error_log to debug in our configuration examples by default.

e.g.: https://github.com/nginx/documentation/blob/main/content/waf/install/docker.md#multi-container-configuration

For example:

Change this:

error_log /var/log/nginx/error.log debug;

to this:

error_log /var/log/nginx/error.log warn;

Alternatively, we can omit the log level, allowing the default level - error.