Sample data ingestions fails when cluster.routing.allocation.awareness.balance enabled

[ohltyler]

This change in core OpenSearch, when enabled, causes validation failures when ingesting sample data for sample detectors:

[Validation Failed: 1: expected total copies needs to be a multiple of total awareness attributes [3];]"

This is due to some hardcoded index settings when creating the sample indices, including auto_expand_replicas being set to "0-1". Note that this logic was originally carried over from core Dashboards, which has the identical problem and is detailed in this issue

We need to finalize the approach for preventing this failure, either by

1. changing these defaults
2. automatically generating them based on cluster configuration (node count, AZ count, etc.)
3. consuming settings from core Dashboards when it is fixed there

We can follow the core Dashboards issue and when that is resolved, proceed with a fix here.

[ohltyler]

As mentioned in dashboards issue - we will rely on the defaults to determine how many replicas should be created upon index creation. From our end, we can simply remove the overridden auto_expand_replicas and consume the cluster setting.