Inaccurate outcome when flushing replays

[billyvg]

Description

In the _runFlush() method, we have a try/catch around a block of code that emits the following 2 outcomes: ratelimit_backoff and send_error.

However, within the try block we are throwing an unrelated exception when the session is too long and not attempted to be sent at all.

It would be nice if we could record this as a separate outcome so that we can use it to debug cases where a replay is not sent.

[linear[bot]]

JS-1213