systemsettingsrunner: Fix all matches having the same id

The id is used by KRunner to increase the relevance for often launched KCMs.

Test Plan:
Delete ~/.local/share/krunnerstaterc
build + install this commit and restart KRunner
launch a few KCMs using KRunner
The `~/.local/share/krunnerstaterc` file should contain LaunchCount
entries with the following pattern: `<count> krunner_systemsettings_<id of KCM>`


(cherry picked from commit cc238c19)