Jingle SOCKS5 fallback does not work correctly if Gajim is the initiator

This is similar, but different from #9692 (closed), where a different problem happens if Gajim is the responder for a SOCKS5 to IBB fallback.

Versions

• OS: Arch Linux
• Gajim version: 1.1.3
• GTK version: 3.24.10
• Python-nbxmpp version: 0.6.10

Steps to reproduce the problem

1. Inititate a file transfer to an entity.
2. (Ensure that all SOCKS5 candidates fail.)
3. Observe the outgoing transport-replace for IBB by Gajim.
4. Observe the incoming transport-accept by another client (e.g. Dino after https://github.com/dino/dino/pull/592 is merged).

Expected behavior

Gajim opens the in-band bytestream (as it is the initiator).

Actual behavior

Nothing happens after the transport-accept is acknowledged by Gajim.