[Remote Store] Integration test scenarios

[sachinpkale]

Describe the solution you'd like
List down various integration test scenarios for the remote store implementation. This includes remote translog as well as remote segment store.

Setup flow

• Remote store feature is behind feature flag. To use the feature, the corresponding feature flag (opensearch.experimental.feature.remote_store.enabled) needs to be enabled.
• In V1, remote store is supported only for those indices which are created new and with settings remote_store=true
• remote_store is a final setting and can't be changed once an index is created.
• A snapshot repository with the same name as cluster UUID needs to be created before

Test Cases

• Create index with remote_store: true feature flag disabled.
• Create index with remote_store: true feature flag enabled without creating remote store repository.
• Create index with remote_store: true feature flag enabled after creating remote store repository.
• Edit existing index by changing remote_store settings.

Indexing Flow

Restore Flow