Allow changing the way of injecting the histogramQuantile binary into the clickhouse container on an air-gapped environment

[Sinhyeok]

The method of downloading the histogramQuantile binary from github.com and copying it to the shared-binary-volume does not work in an air-gapped environment. And in our environment, we don't have any repositories that are open to the public, so even downloading files with wget requires a credential.

Can you extract the setting, initContainer.udf.command from clickhouse chart to values.yaml so that I can override it?