[#1428] Final code cleanup

- Removed caching from getAllX functions in HostMgr
- Renamed setIPReservationUnique to setIPReservationsUnique

src/lib/dhcpsrv/pgsql_host_data_source.h

@@ -504,7 +504,7 @@ public:
     /// unique within the subnet or can be non-unique.
     /// @return always true because this backend supports both the case when
     /// the addresses must be unique and when they may be non-unique.
-    virtual bool setIPReservationUnique(const bool unique);
+    virtual bool setIPReservationsUnique(const bool unique);
 
     /// @brief Context RAII Allocator.
     class PgSqlHostContextAlloc {