Create helper method to replace frequent "is streamed span but not a noop streamed span" check

[ericapisani]

Quality of life refactor. We often have to check that a streamed span is also not a noop streamed span, and having a helper function do this would save a lot of code review comments from the bots that we missed the not isinstance(span, NoOpStreamedSpan) check.

[linear-code]

PY-2397