fix file-based ingestion

Signed-off-by: Varun Bharadwaj <varunbharadwaj1995@gmail.com>

Author: varunbharadwaj

plugins/ingestion-fs/src/main/java/org/opensearch/plugin/ingestion/fs/FilePartitionConsumer.java

@@ -90,6 +90,7 @@ private synchronized List<ReadResult<FileOffset, FileMessage>> readFromFile(long
             }
 
             while (currentLineInReader < startLine && reader.readLine() != null) {
+                lastReadLine = currentLineInReader;
                 currentLineInReader++;
             }