Index snapshotting default values and REST API/CLI ways to change them.

Affected pages:
https://docs.couchbase.com/server/current/rest-api/post-settings-indexes.html
https://docs.couchbase.com/server/current/cli/cbcli/couchbase-cli-setting-index.html#examples

The default values, as well as the ways to change both disk and in-memory index snapshot are not entirely correct.

When it comes to plasma and MOI indexes, by default, indexer creates an in-memory snapshot every 10ms and a disk snapshot every 10mins.

The 5000 value (although it still should me ms, rather than s) is only for forestDB (CE edition).

The way to change the default disk snapshot value for MOI indexes is as follows:

curl -X POST http://<host>:9102/settings/

  -u <username>:<password>

  -d '{"indexer.settings.persisted_snapshot.moi.interval":<integer_in_ms>}'

However we should consider if we want to document this as this is generally not a recommended change.

I'm not sure if the ways listed in the above documentation pages to change the memory/disk snapshotting are correct for Plasma, or if those ways are outdated and applicable only to forestDB as well.

Discussion on the context of the Index snapshotting behaviour/functionality:

https://couchbase.slack.com/archives/CFM4D3VFU/p1723633304712169

https://couchbase.slack.com/archives/CFM4D3VFU/p1691092961752279