Stop caching Repository#exist? in Redis
Right now, we store a lot data in Redis. Among other things, if a repository exists.
This check is really cheap for Gitaly, with the mean response time being .5ms. And the 95 percent tile often not exceeding 10ms. Not caching in Redis anymore will mean that we store less data in it, but also the flow in case of cache misses will be faster.
At the moment, we don't have hit rates on this, so further analyses must be conducted at a later stage.
/cc @andrewn