Test case: "send a text message split into two fragments, then a continuation
frame with FIN = false where there is nothing to continue, then an unfragmented
text message, all sent in one chop".
The test case investigates immediate connection closing since there is no
message to continue.
The mirror server may send a response for the first frame before the test
сontinuation frame is received by the router. In this case, the test will
receive a text frame before the close frame.
After WebSocket processing, the application port was released with incorrect
reason ("got request"), unnecessarily decrementing the active request counter.
The assertion was triggered only on application removal; a test was added
for this case.
