Queued flag isn't cleared after the 5th failed extraction, so inline extraction never runs again

Problem/Motivation

When inline extraction fails, FilesExtractor::queueItem() sets a flag in the search_api_attachments:queued key-value collection and queues the file. FilesExtractor::extractOrGetFromCache() skips inline extraction while that flag is set.

ExtractorQueue::processItem() only clears the flag on success. After the 5th failure it logs and drops the item, but the flag stays:

else {
  $message_params['@message'] = $exception->getMessage();
  $this->logger->log(LogLevel::ERROR, 'Text extraction failed after 5 attempts @file_id for @entity_type @entity_id: @message.', $message_params);
}

So once a file hits 5 failures, inline extraction never runs for it again, even after the extractor is fixed. Happens with any extractor.

Steps to reproduce

1. Point the Tika server extractor at a port with nothing listening.
2. Index an entity with a file field. Extraction fails and the file gets queued.
3. Run cron until the search_api_attachments queue is empty. The log shows "Text extraction failed after 5 attempts".
4. Fix the extractor config and reindex the entity.
5. The file is indexed without text, and the flag is still in key_value under search_api_attachments:queued.

Proposed resolution

Clear the flag on the final failure too. The MR moves the existing cleanup into ExtractorQueue::clearQueuedFlag() and calls it from both the success and final-failure paths. Kernel test included.

Remaining tasks

Review the MR.

User interface changes

None

API changes

None

Data model changes

None