[Core HTTP] Token refresher is not shared among multiple requests

PR https://github.com/Azure/azure-sdk-for-js/pull/10085 introduced a change in core-http in which new requests might trigger delayed token refreshes. These delayed requests might take more time than the tests take to finish, ending up resolving after the recorder wraps up on the afterEach. Here’s some form of diagram:

BEFORE

    All test requests finished before the test finished
    1 Request -> 1 Entry in the recording file

AFTER

    Some requests might happen asynchronously
    1 requests before the test finishes -> 1 Entry in the recording file
    1 Delayed request -> No entry in the recording file

This causes the playback runs to show requests that failed, since playback can’t find the recording. However: the test themselves don’t fail, because they completed successfully before this delayed request happened.

One interesting thing is that playback is able to see these extra requests happening, but recording does not. I’m not sure how useful is that.

[HarshaNalluru]

With #10728, there would be no delayed requests(such as the ones happening after the test) which is what this issue is originally created for. It is logically possible to have such request after the test, but with the current configuration of 30s limit for the token refreshing, it is highly unlikely that our tests would hit the issue. Also, the time taken for the tests would be different in record vs playback modes, which would mean the token refreshing that might happen in record won’t happen in playback. Given the above, we won’t be adding any support to record the requests that are beyond the test(happening outside the test run).

[HarshaNalluru]

Updated the label and the title to reflect the current status of investigation.