Bucket creation should default to CAS based CR

Since XDCR introduced CAS-based conflict resolution, it has always been an opt-in, as during bucket creation the default option is to select Rev-ID seqno based conflict resolution (Most Write Wins).

This ticket is a request to change the default of new bucket creation to use CAS-based CR for two reasons:

1. Better intuitive understanding of conflict resolution behavior
2. Preventing friction for future XDCR replication once serverless is introduced.

1.
Rev-ID based CR is easier to deploy as it doesn't require NTP, but it causes many headaches over the years (via support tickets, or needing repeated explanations), as it is less intuitive to understand when things don't replicate. Often times, this is due to documents being deleted on the target cluster, which turn them into tombstones with a higher revID than the original source document.

I don't have the numbers here, but anecdotally (from history) the majority of the CBSEs being investigated for XDCR document mismatch are using RevID based CR.

2.
https://couchbasecloud.atlassian.net/browse/AV-43778 is a ticket describing that new buckets will now be using LWW by default on serverless. It would be good to also do the same on the server side (for the new buckets being created), to align with the future strategy. More specifically, we want to be able to support XDCR replication to serverless in the future. And, if on-prem deployment is not also defaulting to LWW, it could lead to friction for migration to serverless, and vice versa (i.e. offloading from serverless to on-prem).