Spans should not have the Tracer name as a prefix for their names. This
removes the `spanNameWithPrefix` function and instead passes through the
span name unmodified wherever this had been called.
Tests that checked Span names are updated to have the non-prefix
expected names.
* handle race condition: close handled before open
* add dummy noop span.
* add test for clienttrace
* accept multiples `ConnectStart`/`ConnectDone` trace hooks.
* formatting
* change argument name and add error/attributes to end method.
* add tests for connection race condition
