[qtcontacts-sqlite] Revert "[qtcontacts-sqlite] Fix: Check for read/write capability using QFileInfo"

This reverts commit 19b030ba6ffeca151729dfc0d5ace47a13027903.

This change caused some processes to fail to gain access to the privileged
database when launched from lipstick, even though the same application
launched from a privileged shell could access the privileged database. The
problem does not affect all users.

Conflicts:
	src/engine/contactsdatabase.cpp