MdeModulePkg/UefiBootManagerLib: Convert BmLoadOption to Variable Policy

MdeModulePkg/UefiBootManagerLib: Convert BmLoadOption to Variable Policy

Since the Variable Lock protocol is deprecated, convert locking of
PlatformRecovery#### in EfiBootManagerLoadOptionToVariable to use the
Variable Policy protocol.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhichao Gao <zhichao.gao@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Signed-off-by: Rebecca Cran <quic_rcran@quicinc.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>