Follow up to #14132

[lukebakken]

#14132 introduced a small bug in the JSON output that was caught by CI.

[lukebakken]

I'm running the failed CI suite locally to ensure this is fixed 😬

Failure:
https://github.com/rabbitmq/rabbitmq-server/actions/runs/15880235422/job/44778346713#step:11:6136

JSONFormattingTest [test/json_formatting_test.exs]
  * test JSON output of cluster_status [L#45]
  * test JSON output of cluster_status (33.9ms) [L#45]

  1) test JSON output of cluster_status (JSONFormattingTest)
     test/json_formatting_test.exs:45
     Assertion with == failed
     code:  assert doc["alarms"] == []
     left:  ""
     right: []
     stacktrace:
       test/json_formatting_test.exs:61: (test)

  * test JSON output of status [L#21]
  * test JSON output of status (68.0ms) [L#21]

  2) test JSON output of status (JSONFormattingTest)
     test/json_formatting_test.exs:21
     Assertion with == failed
     code:  assert doc["alarms"] == []
     left:  ""
     right: []
     stacktrace:
       test/json_formatting_test.exs:42: (test)

Not easy to find in the output!

[lukebakken]

Everything passes locally! Sorry for the extra PR:

Finished in 1501.6 seconds (3.8s async, 1497.8s sync)
1414 tests, 0 failures

[ikavgo]

Thank you Luke!