NetworkPkg: Use the New Functions from HttpLib

NetworkPkg: Use the New Functions from HttpLib

After submitting changes for HttpLib, other modules should be able to use
those functions
1 remove the private function and their calls
2 update it with the functions from httpLib

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ghazi Belaam <Ghazi.belaam@hpe.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Samer EL-Haj-Mahmoud <elhaj@hpe.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>