LogConfigurator resolveConfig  also reads .rpmnew or .bak files

Currently the LogConfigurator will attempt to read any file that starts with "logging." in the env.configFile() path.

A common practise is to suffix files with .bak or in case of package managers they often add a suffix if the file has been modified upstream.

Elasticsearch will read those values anyway and that might lead to very confusing logging behaviour.

I am not sure how to best approach this, either have a whitelist or a backlist of suffixes that are allowed/disallowed ?
@uboness you replied to and outdated comment, have a look at [this](https://github.com/elasticsearch/elasticsearch/pull/7457#issuecomment-62705392) other comment to see what we settled on. If I read your comment right, that should be ok.