C++: Also remove TInitializeThisValueNumber from the AST wrapper

Author: MathiasVP

cpp/ql/src/semmle/code/cpp/ir/internal/ASTValueNumbering.qll

@@ -84,8 +84,6 @@ class GVN extends TValueNumber {
     or
     this instanceof TInitializeParameterValueNumber and result = "InitializeParameter"
     or
-    this instanceof TInitializeThisValueNumber and result = "InitializeThis"
-    or
     this instanceof TStringConstantValueNumber and result = "StringConstant"
     or
     this instanceof TFieldAddressValueNumber and result = "FieldAddress"