[Proposal] Extend ulimit max open file detection to clients or consider tuning the rocksdb parameters

[HarukaMa]

💥 Proposal

Basically, 1024 max open files will not be enough even for clients in a few month's time. It's probably a good idea to check the ulimit for clients as well. A more future proof value would be around 8192 or higher (it really doesn't matter that much in modern systems).

Or, we could probably tune the parameters of rocksdb. Not sure if this is desired though.