MdeModulePkg PlatformVarCleanupLib: Locate VarCheck protocol when using

MdeModulePkg PlatformVarCleanupLib: Locate VarCheck protocol when using

Do not locate VarCheck protocol in Constructor, then the
gEdkiiVarCheckProtocolGuid could be removed from [Depex].
It will be more flexible for the library Consumer to work without VarCheck
protocol installed, for example at recovery boot mode with EmuRuntimeDxe.

The unused UefiLib is also been removed from [LibraryClasses] in *.inf.

Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>