[fix](routineload) Preserve cloud progress for Kafka property alters

[0AyanamiRei]

What problem does this PR solve?

Issue Number: None

Related PR: None

Problem Summary: In cloud mode, every ALTER ROUTINE LOAD ... FROM KAFKA(...) operation reset the persisted routine-load progress. For Kafka client-property-only changes such as group.id or client.id, the reset request contained no partition offsets, so Meta Service deleted the complete progress record. After FE replay, resuming the job could reconstruct offsets from the default end position and skip the paused backlog while still reporting RUNNING.

This change preserves existing cloud progress for Kafka client-property-only alterations. Progress is still reset when the topic or explicit partition offsets change.

Release note

Kafka client-property-only routine load alterations now preserve cloud consumption progress across FE replay and resume.

Check List (For Author)

• Test: Unit Test added; not run as requested
• Behavior changed: Yes. Kafka client-property-only ALTER no longer resets cloud routine-load progress.
• Does this need documentation: No

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