Upgrade Couchbase Client to 2.7.23

The Java Couchbase Client version 3 is the current supported version, but includes a number of breaking changes. Version 2 of the client is still receiving maintenance updates, and project modules should be updated to the latest version of the 2.7 release line, which provides broad compatibility with Couchbase Server versions.

https://docs-archive.couchbase.com/java-sdk/2.7/compatibility-versions-features.html