Drop clickhouse-grpc-client

[zhicwu]

gRPC has been available as an experimental feature in ClickHouse for a while, but it lacks active maintenance, likely due to its limited usage. In this repository, the clickhouse-grpc-client was primarily developed to test interfaces in clickhouse-client. However, this addition introduces a multitude of dependencies into a relatively small library, resulting in intermittent build failures during continuous integration. Consequently, it is not recommended for production usage due to issues such as inadequate lz4 support and excessive server memory consumption.

Speaking from my personal experience at a company that follows the "use it or lose it" philosophy, I strongly advise removing the clickhouse-grpc-client. This action would not only resolve the CI build failures and eliminate unnecessary dependencies but also eliminate any confusion for users.

Lastly, I would like to mention that Apache Arrow Flight might be a more viable alternative. We can revisit this topic when ClickHouse/ClickHouse#7554 is implemented.