[FLINK-32893][Connectors/Kafka] Allow the clientid to be fully configurable

[bdbene]

What is the purpose of the change

FLINK-32893 There's some use cases to use the same clientID across all of the low level Kafka consumers to

1. Simplify how quotas are applied
2. Lower the cardinality of metrics reported by the Kafka brokers

Brief Change Log

Support an optional configuration for the exact clientID to run Kafka consumers with

Verifying this change

It's difficult to write unit tests for this which is probably why there's no existing unit tests for the client ID. However I was able to run this locally and could see the client ID was logged exactly as I specified it (no prefix or suffix).

[boring-cyborg[bot]]

Thanks for opening this pull request! Please check out our contributing guidelines. (https://flink.apache.org/contributing/how-to-contribute.html)

[MartijnVisser]

@bdbene Can you please rebase your PR?

[bdbene]

Done :)

[MartijnVisser]

@bdbene Please rebase instead of merging, since we can't merge in merge commits

[bdbene]

Oops, fixed that