fix: handle most recently created containers first

[buchdag]

trafficstars

This is a proposed fix for #1049. It orders the containers being iterated over by descending creation timestamp (most recent first) instead of by ascending certificate domain name.

Closes #1049

[buchdag]

@cpontvieux-systra I know this is ~ 4 months old but your help in validating that this fix #1049 would be welcome.

I've pushed and image that include the fix : nginxproxy/acme-companion:1049