dns_dispatch, StreamDNS: using wrong TID

There seems to be something wrong with StreamDNS:

https://isc-projects.gitlab-pages.isc.org/-/bind9/-/jobs/3038067/artifacts/tsan/0bb7786588a6d9b258264c88ff7e4f306abf60a63b28ff031cc303ef6c881c17/7457c78fe2678b385ad06816819d677dab023552a940e09d71d5045feb24e7c1.txt

This is on a ondrej/always-track-netmgr-sockets-and-handles branch; here's the job: https://gitlab.isc.org/isc-projects/bind9/-/jobs/3038067

Basically, it exhibits a behaviour where it uses a wrong mempool - I'll add some safety checks into that function, but this should not be happening.