Fix/401 redirect on actuator requests

[ulischulte]

closes #1640, #1691 and probably some other issues connected to redirects to login.

I corrected the predicate inside the redirectOn401 (isInstanceActuatorRequest didn't include the baseUrl and so the predicate never matched).
However - the existance of this predicate suggests that there was previously a reaction to a 401 at actuator endpoints (still don't know why it occurs though).
I added a retry for the subscriptions and the UI seems to be working correctly with these adjustments.

[SteKoe]

in the previous implementation you chose take(5) instead of 2. Is there any reason for doing this? Would it make sense to refactor the whole pipe implementation to a function which can be reused anywhere? Like as follows:

const pipeRetry = (stream) => pipe(concatMap(stream), retryWhen(
    err => {
      return err.pipe(
        delay(1000),
        take(5)
      )
    }));

return timer(0,5000).pipeRetry(vm.fetchHttptrace).subscribe(....);