Make the tracing sampling ratio be 0% by default

[nox]

When Foundations 4 was released, the tracing config changed and some apps ended up with 100% tracing enabled, crashing some downstream processes doing so. Having sampling be 0% by default would avoid that.

[TheJokr]

FWIW I looked at the code in foundations 3.3.0 and I think it was set to 100% before 4.0 as well. But I agree that's not a sensible default.