Used ciphers may not always be reflected in stats output

[oschaaf]

Envoy stopped tracking usage count of all ciphers individually, and as of today now only a select few are tracked. This broke a test in NH and we opted to change to a supported cipher. However, it would be great to have this functionality back again for observation (and possibly automatic verification of) ciphers used.
A first attempt to restore this was proposed over at the Envoy repo [2], but was backed out / closed because of better ways to pull it of where suggested (see PR comments over at [2]).
[1] https://github.com/envoyproxy/nighthawk/pull/149/files/ef212fea98e9d6cce6894dca6a1d7366730adf7e#diff-06285750a6347275084b85de2bbc1311
[2] envoyproxy/envoy#8435

[oschaaf]

Closing this, as this was resolved via envoyproxy/envoy#14534