software/simpleran: Disable output multithreading in eNB fluentbit
For the forward output section of the eNB xlog-fluentbit service, reduce the number of workers from the default value of 2 to 1.
As the service only ever watches one file, the extra worker is unneeded except when it retries to flush data chunks or needs to catch up from the head of the file. In those cases, we should not use multithreading anyway in order to keep the order of the data intact as much as possible.