Previously, when a topic was edited (including being resolved), it
would become unmuted for any users who had muted it, which was
annoying.
While it's not possible to determine the user's intent completely,
this is clearly incorrect behavior in the `change_all` case, such as
resolving a topic.
The comments discuss some scenarios where we might want to enhance
this further, but this is the best we can do without large increases
in complexity.
Fixes#15210.
Co-authored-by: akshatdalton <akshat.dak@students.iiit.ac.in>