[sdk-trace-base] [sdk-trace-node] remove propagator auto-configuration from package

[pichlermarc]

Description

It is currently confusing which packages implement auto-configure and to which extent. We've previously auto-instantiated propagators from sdk-trace-base and sdk-trace-node.

In SDK 2.0 we should move any auto-configuration functionality to @opentelemetry/sdk-node, any only apply direct-code configuration in sdk-trace-base and sdk-trace-node. Therefore we should remove that auto-configuration of propagators from sdk-trace-base and sdk-trace-node and implement it in @opentelemetry/sdk-node instead.

This issue is considered done when

• [ ] auto-instantiation of propagators based on env vars is removed from sdk-trace-base
• [ ] auto-instantiation of propagators based on env vars is removed from sdk-trace-node
• [ ] auto-instantiation of propagators based on env vars is implemented in sdk-node