[meta.reflection.{layout, annotation}] Harmonize phrasing about complete types (#8347)

Fixes NB US 107-168 (C++26 CD).

Author: jensmaurer

source/meta.tex

@@ -5840,8 +5840,8 @@
 direct base class relationship, or
 data member description.
 \item
-If \tcode{dealias(r)} represents a type $T$,
-there is a point within the evaluation context from which $T$ is not incomplete.
+If \tcode{dealias(r)} represents a type,
+then \tcode{is_complete_type(r)} is \tcode{true}.
 \end{itemize}
 \end{itemdescr}
 
@@ -7037,8 +7037,8 @@
 \item
   \tcode{annotations_of(item)} is a constant expression and
 \item
-  \tcode{dealias(type)} represents a type that is complete
-  from some point in the evaluation context.
+  \tcode{dealias(type)} represents a type and
+  \tcode{is_complete_type(type)} is \tcode{true}.
 \end{itemize}
 \end{itemdescr}