Explicitly remove subscription from wait_for WaitSet

[dhood]

Prototype fix for #1101 🤞

[mergify]

@dhood, all pull requests must be targeted towards the master development branch.
Once merged into master, it is possible to backport to ci_noble, but it must be in master
to have these changes reflected into new distributions.

[dhood]

hey guys what's the trick to getting CI to trigger around here 😆
(edit: seems a-go now 👍 ; forgive me for using CI to experiment! no src checkout locally)

[christophfroehlich]

hey guys what's the trick to getting CI to trigger around here 😆

a maintainer has to approve CI for first-time contributors ;)

[dhood]

needed a new commit first to retrigger the CI request, after retargeting to master, first!
but nvm, this approach doesn't work! was optimistic that the issue was at the spinning, but it's before that, which is a harder thing to address.

SO the low-hanging fruit patch didn't conveniently fix this, so I'll close this in favour of a more invasive fix. it's less likely I'll have time for that but not impossible, since I am nerd-sniped ;)