Cherry-pick elastic#10541 to 6.x: Do not read last entry when falling…

… back to tail (elastic#10554)

Previously, when falling back to tail seeking mode, the last entry was read by Journalbeat. This could lead to unwanted events being read, when a user simply wants to read new entries.
It was already fixed in case of tail seek mode.

This feature hasn't been released yet, so I am not adding a new changelog entry.

reader/journal.go

@@ -160,6 +160,7 @@ func (r *Reader) seek(cursor string) {
 				r.logger.Debug("Seeking method set to cursor, but no state is saved for reader. Starting to read from the beginning")
 			case config.SeekTail:
 				r.journal.SeekTail()
+				r.journal.Next()
 				r.logger.Debug("Seeking method set to cursor, but no state is saved for reader. Starting to read from the end")
 			default:
 				r.logger.Error("Invalid option for cursor_seek_fallback")