Zero out parent rule when overridden by local property.

Fixes https://gitlab.com/kicad/code/kicad/issues/11197

(cherry picked from commit b679a21651)

pcbnew/drc/drc_engine.cpp

@@ -1133,6 +1133,7 @@ DRC_CONSTRAINT DRC_ENGINE::EvalRules( DRC_CONSTRAINT_T aConstraintType, const BO
 
         if( localA > global || localB > global )
         {
+            constraint.SetParentRule( nullptr );
             constraint.SetName( m_msg );
             constraint.m_Value.SetMin( clearance );
             return constraint;