lib/logstorage: duplicate stream fields can panic during ingestion

[func25]

Describe the bug

VictoriaLogs v1.51.0 and earlier can store logs with duplicate stream fields. After #1504, MustAdd still allows these duplicates, but the validation later panics when single-node VictoriaLogs registers the stream.

The problem is that cluster mode behaves differently, vlstorage drops the row in MustAddInsertRow instead of panicking. MustAdd should reject duplicate stream fields consistently with MustAddInsertRow before passing them to storage.

To Reproduce

Run current master in single-node mode, then send:

curl -H 'Content-Type: application/json' \
  -H 'VL-Stream-Fields: service' \
  --data-binary '{"_msg":"test","service":"foo","service":"bar"}' \
  http://localhost:9428/insert/jsonline

Version

master

Logs

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Screenshots

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Used command-line flags

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Additional information

No response

[func25]

Starting from the commit 664c6c1, VictoriaLogs accepts logs containing duplicate stream field names instead of panicking during ingestion. Duplicate stream tags are currently preserved in the stored logs. A follow-up change will deduplicate all fields with duplicate names, including stream fields, by keeping only one field per name. See #1286.

This commit will be included in the next release of VictoriaLogs. In the mean time it is possible to verify the fix by building VictoriaLogs from the commit according to these instructions.