ns-phonehome: fix json format

[gsanchietti]

The distro node is required, otherwise the server will not accept the payload.

Regression introduced in commit 2b9e1d1251924562d90ec8a8514b70d816519f05

Server error:

n1 app[1492815]: [2024-05-16 12:49:38] production.DEBUG: JsonSchema validation failed {"/facts":["The required properties (distro) are missing"]}