[expr.prim.id.general] Unindex id-expression as text (#9012)

The grammarterm in the same paragraph is already indexed.

Author: timsong-cpp

source/expressions.tex

@@ -1381,7 +1381,6 @@
 
 \pnum
 \indextext{name}%
-\indextext{id-expression}%
 An \grammarterm{id-expression} is a restricted form of a
 \grammarterm{primary-expression}.
 \begin{note}