identity: use g_hash_table_unref not g_clear_object
identity: use g_hash_table_unref not g_clear_object

the identity service finalize function is using
g_clear_object on hash tables, which is incorrect.

This commit changes the g_clear_object calls to use
g_clear_pointer and g_hash_table_unref instead.

https://bugzilla.gnome.org/show_bug.cgi?id=709103

Distrotech/gnome-online-accounts,ritzk/gnome-online-accounts,dnohales/gnome-online-accounts,halfline/gnome-online-accounts,halfline/gnome-online-accounts,Distrotech/gnome-online-accounts,felipeborges/gnome-online-accounts,dnohales/gnome-online-accounts,halfline/gnome-online-accounts,ritzk/gnome-online-accounts,Distrotech/gnome-online-accounts,felipeborges/gnome-online-accounts,felipeborges/gnome-online-accounts,ritzk/gnome-online-accounts,dnohales/gnome-online-accounts