cdc: compression option for Kafka needs to be in all caps

[HonoreDB]

Aaron Zinger (honoredb) commented:

Support issue: https://github.com/cockroachlabs/support/issues/2208

Our docs give the example Kafka config "Compression": "gzip". This errors out, though. The valid values are "NONE", "GZIP", "SNAPPY","LZ4", and "ZSTD".

Jira Issue: DOC-7400