[conv.fpint] Remove duplicate UB label

Author: jensmaurer

source/expressions.tex

@@ -1017,7 +1017,7 @@
 exactly as a value of the floating-point type.
 \end{note}
 If the value being converted is
-outside the range of values that can be represented, the behavior is undefined\ubdef{conv.fpint.not.represented}. If the
+outside the range of values that can be represented, the behavior is undefined. If the
 source type is \keyword{bool}, the value \keyword{false} is converted to zero and the value
 \keyword{true} is converted to one.