patch 8.2.0016: test name used twice, option not restored properly

Problem:    Test name used twice, option not restored properly.
Solution:   Rename function, restore option with "&".
diff --git a/src/testdir/test_textformat.vim b/src/testdir/test_textformat.vim
index 1364dd7..2223be9 100644
--- a/src/testdir/test_textformat.vim
+++ b/src/testdir/test_textformat.vim
@@ -906,7 +906,7 @@
 endfunc
 
 " Test for 'whichwrap' with multi-byte character
-func Test_whichwrap()
+func Test_whichwrap_multi_byte()
   new
   let t =<< trim END
     á
@@ -917,7 +917,7 @@
 
   set whichwrap+=h
   normal dh
-  set whichwrap-=h
+  set whichwrap&
 
   let expected =<< trim END
     áx