Improve Backpressure Management

[stephanie-anderson]

Description

Please see the project issue for further details: getsentry/team-sdks#10

[adinauer]

We're looking for customers to give this a try in a backend application environment. If you'd like to do so, please let us know.

It allows you to set a tracesSampleRate of 1.0 and reduce the rate in case the system is under load to reduce the overhead we cause.