[juniper_junos.log] field "log.file.device_id" is undefined

There is a CI test failure under 8.13. 

`system test: logfile in juniper_junos.log:`

`one or more errors found in documents stored in logs-juniper_junos.log-ep data stream: [0] field "log.file.device_id" is undefined
[1] field "log.file.inode" is undefined`

https://buildkite.com/elastic/integrations/builds/10363
https://buildkite.com/elastic/integrations/builds/10563