[fix](cloud) Skip empty rowsets before accessor lookup in batch delete_rowset_data

[liaoxin01]

Proposed changes

In batch delete_rowset_data, empty rowsets (e.g. base compaction output of empty rowsets) have num_segments=0 and no resource_id set. The accessor_map_.find("") fails and sets ret=-1, which causes the caller to skip txn_remove for the entire batch. This prevents recycle KV keys from being cleaned up, creating a perpetual loop where the same rowsets are scanned every recycle round.

The fix moves the num_segments <= 0 check before the accessor_map_ lookup so these empty rowsets are safely skipped without poisoning the batch return value.

Problem summary

• Empty rowsets from base compaction have resource_id="", rowset_meta_size=181, num_segments=0
• accessor_map_.find("") fails, sets ret = -1, txn_remove skipped for entire batch
• Normal rowsets in the same batch: object storage data already deleted, but recycle KV not cleaned up
• Next recycle round re-scans the same rowsets, forming a dead loop

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[Copilot]

Pull request overview

Fixes batch delete_rowset_data behavior in the cloud recycler by skipping empty rowsets (e.g., base compaction outputs with num_segments=0 and unset resource_id) before doing an accessor_map_ lookup, preventing a spurious batch failure that can block recycle KV cleanup and cause repeated rescans.

Changes:

• Move the num_segments <= 0 early-continue check ahead of accessor_map_.find(rs.resource_id()) in batch rowset deletion.
• Add explanatory comments describing the failure mode and why the ordering matters.

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[liaoxin01]

run buildall

[doris-robot]

Cloud UT Coverage Report

Increment line coverage 33.33% (2/6) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	79.35% (1798/2266)
Line Coverage	64.75% (32177/49697)
Region Coverage	65.60% (16096/24537)
Branch Coverage	56.14% (8579/15282)