Snowflake Broker IP Change Rate Data HMAC Key Used the default value

This is an issue discovered in the #40151 (closed) 's configuration that the ip-count-mask used the default value, and make the counting result unsuitable for publishing.

I will deploy it again tomorrow with a randomly generated HMAC key. The collected unsalted IP count data will be retained and used for internal research only. It is not useless either, since it has collected data for over a month, and could be used for validation of this feature.