MdeModulePkg: Change complex DEBUG_CODE() to DEBUG_CODE_BEGIN/END()

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3767

Update use of DEBUG_CODE(Expression) if Expression is a complex code
block with if/while/for/case statements that use {}.

Cc: Andrew Fish <afish@apple.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Michael Kubacki <michael.kubacki@microsoft.com>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdeModulePkg/Universal/Variable/Pei/Variable.c

@@ -512,7 +512,7 @@ GetHobVariableStore (
   //
   // Make sure there is no more than one Variable HOB.
   //
-  DEBUG_CODE (
+  DEBUG_CODE_BEGIN ();
     GuidHob = GetFirstGuidHob (&gEfiAuthenticatedVariableGuid);
     if (GuidHob != NULL) {
       if ((GetNextGuidHob (&gEfiAuthenticatedVariableGuid, GET_NEXT_HOB (GuidHob)) != NULL)) {
@@ -531,7 +531,7 @@ GetHobVariableStore (
         }
       }
     }
-  );
+  DEBUG_CODE_END ();
 
   GuidHob = GetFirstGuidHob (&gEfiAuthenticatedVariableGuid);
   if (GuidHob != NULL) {