faaa7db qa: Only allow disconnecting all NodeConns (MarcoFalke)
Pull request description:
Disconnecting the connection with `index=0` makes no sense when there are more than one connections, as the list "rotates around" and populates index 0 after `del`.
Just disconnect all NodeConns in any case.
Tree-SHA512: e5cf540823fccb31634b5a11501f54222be89862e80ccafc28bc06726480f8d2153b8c1b6f859fa6a6d087876251d48a6c6035bccdaaf16831e300bc17ff613d