What this PR does / why we need it:

The ClickHouse offline store example uses a fully qualified store class as type, but ClickhouseOfflineStoreConfig accepts only clickhouse. After replacing the connection placeholders, copying the example still produces a configuration validation error.

Use the existing clickhouse alias. It resolves to the same store class and satisfies its configuration model.

Which issue(s) this PR fixes:

No linked issue. This does not change ClickHouse query generation covered by #6775 / #6141.

Checks

• I've made sure the tests are passing.
• My commits are signed off (git commit -s)
• My PR title follows conventional commits format.

Testing Strategy

• Unit tests
• Integration tests
• Manual tests
• Testing is not required for this change

Parsed both YAML examples with existing PyYAML 6.0.3. With DB_PORT replaced by integer 8123 in both inputs, the unchanged source definitions of FeastConfigBaseModel, ClickhouseConfig, and ClickhouseOfflineStoreConfig were executed using existing Pydantic 2.12.5: the original reports only a type literal error; the updated example passes. The unchanged source store-type selector resolves both values to the same class. git diff --cached --check passes.

This is isolated source-model validation. Full Feast/RepoConfig integration, CLI, unit suite, ClickHouse connections, and Sphinx were not run.

Release notes

NONE