core: Remove the general provider type

The general provider type is redundant and is not used anymore.
It was used in the past as an attempt to perform auto detection
to learn about the ldap vendor, but this mechanism was already depracated.

Bug-Url: https://bugzilla.redhat.com/1058011
Change-Id: I3414673e2300d44a30ad00ac2acf6762bcdb0700
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>