[websockets] some tests fixes

But they still don't work because there is no HasClient implemented
for the websocket server.
Status Job ID Name Coverage
  Cabal
failed #13470
cabal

 
  Stack
skipped #13471
stack
 
  Bench
skipped #13472
allowed to fail manual
bench
 
  Test
skipped #13473
test
 
Name Stage Failure
failed
cabal Cabal There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job trace