[REG 6.0.2 -> 9.0.2] Renaming class from code completion doesn't work correctly

1. In a CppEditor, type "class".
2. If it doesn't appear automatically, trigger code completion.
3. From the list of proposals, select "class derived from QObject" and press Enter.
   A class called "name" is inserted into the file.
4. Type a different name.

Expected result: While you are typing, the class' ctor and dtor update accordingly. This works in Qt Creator 6.0.2.

Actual result: Only the class' name changes while you are typing. The ctor and dtor don't change.

Found and tested by Squish test tst_CSUP02.