Problem:
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- This commit is a merge of mysql commit 129ee47ef994652081a11ee9040c0488e5275b14.
InnoDB FTS can be in inconsistent state when sync operation
terminates the server before committing the operation. This
could lead to incorrect synced doc id and incorrect query results.

Solution:
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- During sync commit operation, InnoDB should pass
the sync transaction to update the max doc id
in the config table.

fts_read_synced_doc_id() : This function is used
to read only synced doc id from the config table.