Automation traces should not indirectly call Fn.getNextId() when it's in an automation chain

If Fn.getNextId() is called in an automation chain and the automation trace are enabled, Fn.getNextId() should not be called a second time to generate traces.

How to reproduce:

• activate automation traces in nuxeo.conf (org.nuxeo.automation.trace=true)
• define a new automation chain with the following YAML:

  - Context.FetchDocument
  - LogOperation:
      level: warn
      message: "[SUPNXP-13306] getNextId(): @{Fn.getNextId(\"SUPNXP-13306\")}"
      category: RunScript
  

• define an event handler calling the automation above when a File is created
• create 2 documents of type File
  In server.log you can see that the the sequence ID SUPNXP-13306 is incremented 4 times, playing the above scenario with org.nuxeo.automation.trace=false shows that sequence ID SUPNXP-13306 is incremented only twice.