Improve the Error message and log level of "LuceneIndexSnapshotException: No snapshot found in shared home for index MAIN_INDEX with journal entry id xx." in JournalSystemMaintenanceTaskQueue

Issue Summary

When a new node added to Confluence DC cluster with no local home like launching via AWS AutoScaling(related ticket: CONFSERVER-81250 ), the new node will try to find index snapshots from journal_entry table records.

However, old index snapshot files and old journal records will be removed by Clean Journal Entries job, but the following error log will be occured in some situations.
The level of this log is "ERROR", so system administrator wants to check this log is harmful or not, but there is no description what should they do in this error message.

• Error Message in atlassian-confluence.log

  20XX-XX-XX XX:XX:XX,XXX ERROR [Caesium-1-2] [confluence.impl.system.JournalSystemMaintenanceTaskQueue] processEntriesInternal Encountered an unrecoverable error while executing the system task. This task will be skipped. 'JournalEntry{id=xx, journalId=JournalIdentifier{journalName=system_maintenance}, creationDate=Thu Oct XX XX:XX:XX UTC 20XX, type=RESTORE_INDEX_SNAPSHOT, message={"sourceNodeId":"xxxxxxxx","indexSnapshots":[{"index":"MAIN_INDEX","journalId":xx},{"index":"CHANGE_INDEX","journalId":xx}]}}'
  com.atlassian.confluence.internal.index.lucene.snapshot.LuceneIndexSnapshotException: No snapshot found in shared home for index MAIN_INDEX with journal entry id xx.
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Please improve thee error message of "LuceneIndexSnapshotException: No snapshot found in shared home for index MAIN_INDEX with journal entry id xx." in JournalSystemMaintenanceTaskQueue.

This is reproducible on Data Center: yes

Suggest

Giving the information what should sysadmin(Confluence system maintainer) do or check when they got this error message.

Actual Results

The customer can't judge with this error log whether immediate action is required or not without the knowledge of how Confluence DC cluster index work.

Workaround

If you can't judge this error whether action is required or not, please contact to Atlassian Support.