Deprecate/remove `traceSampling` flag in favor of `tracePropagationTargets`

### Description

Ideally done with https://github.com/getsentry/sentry-java/issues/2243

We could make this flag enabled by default for now if its much easier/faster.
Since this flag is not documented, its more important to have it enabled otherwise DS won't work.