[Feature] Аdd a metric for clickhouse proxy responses

[NatSau02]

Is your feature request related to a problem? Please describe. When sending concurrent queries with a syntax error, the response "500, concurrent query failed" is returned, although the clickhouse responds to such errors with 400 (screenshot). I would like to know information about the real answers of the clickhouse proxy

Describe the solution you'd like I added a metric for clickhouse responses

Describe alternatives you've considered here https://github.com/ContentSquare/chproxy/issues/404 it was described how to solve this problem by changing the final response codes. I suggest another simpler solution, which is to add a metric. These are two different solutions to the same problem, after solving any of them, the second one can be automatically closed

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