Traces are propagated if tracing is disabled

[quaff]

According to #38625 (comment), management.tracing.enabled is used to disable tracing only in tests currently, If we want to dynamic disable tracing entirely we have to exclude AutoConfiguration by spring.autoconfigure.exclude, That's not handy especially for profile combination.

[philwebb]

We discussed this today and we'd like to make it so that management.tracing.enabled also disables the propagation of traces (probably by adding conditions to brave and otel beans).