Clean the Qt4 i18n branch for a few repositories

Do not track anymore the last Qt4 version for those libraries.
The translations haven't been extracted for a long time (and kdelibs
hasn't been handled anyway for a while).

projects-invent/frameworks/kactivities/i18n.json

-{"stable": "KDE/4.13"}
+{"trunk_kf5": "master"}

projects-invent/frameworks/kpeople/i18n.json

-{"stable": "libkpeople-0.3"}
+{"trunk_kf5": "master"}

projects-invent/frameworks/modemmanager-qt/i18n.json

-{"stable": "MM/1.0"}
+{"trunk_kf5": "master"}

projects-invent/frameworks/networkmanager-qt/i18n.json

-{"stable": "NM/0.9.8"}
+{"trunk_kf5": "master"}