Add property to disable the OpenTelemetry SDK

[mhalbritter]

The property should behave like the OTEL_SDK_DISABLED variable, only negated.

OTEL_SDK_DISABLED: If “true”, a no-op SDK implementation will be used for all telemetry signals. Any other value or absence of the variable will have no effect and the SDK will remain enabled. This setting has no effect on propagators configured through the OTEL_PROPAGATORS variable.

We could use management.opentelemetry.enabled as the name.