patch 9.0.1066: test function name is wrong

Problem:    Test function name is wrong.
Solution:   Rename to what is actually being tested. (closes #11712)
diff --git a/src/testdir/test_menu.vim b/src/testdir/test_menu.vim
index 65bdac2..1247359 100644
--- a/src/testdir/test_menu.vim
+++ b/src/testdir/test_menu.vim
@@ -570,7 +570,7 @@
   tunmenu a.b
 endfunc
 
-func Test_mapclear_while_listing()
+func Test_unmenu_while_listing_menus()
   CheckRunVimInTerminal
 
   let lines =<< trim END