fix(profiler): Stop nulling buffer on teardown by ericapisani · Pull Request #6075 · getsentry/sentry-python

There's still the occasional race condition in the GEvent tests that may be related to fast "start/stop" cycles, and the teardown functions were not updated as part of #5622 (comment)

These changes remove self.buffer = None from teardown() in both ThreadContinuousScheduler and GeventContinuousScheduler in favour of using a local variable to assign self.buffer to before setting the local variable to None

Fixes PY-2140
Fixes #5673