## Motivation and Context
Sampling is a one-to-one request/response interaction between a server and a specific client.
`Server#create_sampling_message` does not scope requests to a specific session, which could
lead to unintended broadcasts on multi-client transports. `ServerSession#create_sampling_message`
should be used instead, as it routes the request to the correct client session.
This aligns with the Python SDK, which also exposes sampling only at the session level.
## How Has This Been Tested?
Existing tests updated to call `ServerSession#create_sampling_message` instead of
`Server#create_sampling_message`. All tests pass (`rake test`), RuboCop is clean,
and conformance tests pass.
## Breaking Changes
`Server#create_sampling_message` is removed without a deprecation warning.
The sampling feature was released recently and the method was not intended
to be the primary API for this feature.
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