(bug 50078) Allow a string other than '*' as condition for DatabaseBase::delete()

Currently, either '*' is given as condition meaning "everything" or an array must
be passed since DatabaseBase::makeList() requires an array. Now the parameter is
consistent with one of other similar methods, since a string will be handled
correctly.

Bug: 50078
Change-Id: Id5a8220d21245669f1091a3b5ed1def65b22d375
(cherry picked from commit b18770232c679482e0c7bf775b84eda5f7f3b782)