Flaky Test: ClientDisconnectCallbackStress

[jkotalik]

Test consistently fails in IISExpress which causes all tests afterwards to fail.

[jkotalik]

This was a side effect of other test failures at the time. We don't see this test failing now. If we see it again (on CI or PR), we can let RAAS reopen an issue.

[pakrym]

The test is still skipped in code.