patch 9.1.0469: Cannot have buffer-local value for 'completeopt'

Problem:  Cannot have buffer-local value for 'completeopt'
          (Nick Jensen).
Solution: Make 'completeopt' global-local (zeertzjq).

Also for some reason test Test_ColonEight_MultiByte seems to be failing
sporadically now. Let's mark it as flaky.

fixes: #5487
closes: #14922

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index 07c416a..6edb889 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2024 Jun 03
+*version9.txt*  For Vim version 9.1.  Last change: 2024 Jun 05
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41567,6 +41567,7 @@
 - use 'smoothscroll' logic for CTRL-D and CTRL-U for half-pagewise scrolling
 - the default for 'commentstring' contains whitespace padding to have
   automatic comments look nicer |comment-install|
+- 'completeopt' is now a |global-local| option.
 
 							*added-9.2*
 Added ~