Preserve Kafka setting during ClickPipe updates

[sdairs]

Summary

• preserve the current kafka_read_committed value when updating unrelated ClickPipe settings
• fail instead of fabricating a value when the tolerant settings response omits the required field
• add subprocess and wiremock coverage for the settings GET to PUT request flow

Verification

• cargo test -p clickhousectl
• cargo clippy -p clickhousectl --all-targets -- -D warnings
• cargo fmt --all --check

[macroscopeapp]

🟠 High cloud/clickpipes.rs:1648

Valid non-Kafka ClickPipes settings updates now fail before the PUT when the GET response omits kafka_read_committed, so changes such as object_storage_concurrency or object_storage_polling_interval_ms are never applied. Since this Kafka-specific field is optional, preserve it when present and use the existing false default when it is absent instead of returning an error.

Suggested change

	.ok_or("the API response is missing kafka_read_committed")?;
	.unwrap_or(false);

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In file @crates/clickhousectl/src/cloud/clickpipes.rs around line 1648:

Valid non-Kafka ClickPipes settings updates now fail before the `PUT` when the GET response omits `kafka_read_committed`, so changes such as `object_storage_concurrency` or `object_storage_polling_interval_ms` are never applied. Since this Kafka-specific field is optional, preserve it when present and use the existing `false` default when it is absent instead of returning an error.