Disable kactivitymanagerd

Question

For context, I don't like my desktop environment tracking my file and app usage history. To that end, I always fully disable this behavior using the relevant system settings. However, it seems that kactivitymanagerd disregards these. It continues to track usage under ~/.local/share/kactivitymanagerd regardless of how user preferences are set.

So far, I haven't managed to figure out how to manually disable this component. It doesn't seem to be managed via systemd (systemctl doesn't show a unit with a matching name) and KDE itself doesn't seem to provide a knob to turn it off. This existing question suggests simply uninstalling the relevant package in order to disable it. However, the Ubuntu plasma-desktop package depends on it and in my case I'm actually using the rest of KDE so direct removal isn't so straightforward.

Initially, I removed the contents of ~/.local/share/kactivitymanagerd and made the directory immutable. However, while this does disable history tracking it also appears to cause kactivitymanagerd to crash on startup. That isn't inherently a problem but some process is incessantly launching it in the background. I don't know how to find the culprit and it results in Apport consuming a constant ~50% CPU cleaning up and writing out a never ending stream of error reports. (This behavior in and of itself seems like a fairly severe bug.)

My stopgap has been to chmod /usr/bin/kactivitymanagerd to be read-only (specifically, no execute). That seems to have successfully alleviated the CPU consumption issue for now but it really seems like the wrong way to accomplish this. In particular, I'm concerned that my "solution" might be automatically undone by apt in the future.

Does anyone know of a better fix? (Distro is Ubuntu 18.04LTS in case it makes a difference.)