patch 9.1.1261: No test for 'pummaxwidth' non-truncated items

Problem:  No test for 'pummaxwidth' non-truncated items (after v9.1.1250)
Solution: Add shorter items to Test_pum_maxwidth_multibyte() (zeertzjq).

closes: #17007

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index e95465c..e216a6d 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -2036,6 +2036,8 @@
       return [
         \ #{word: "123456789_123456789_123456789_"},
         \ #{word: "一二三四五六七八九十"},
+        \ #{word: "abcdefghij"},
+        \ #{word: "上下左右"},
         \ ]
     endfunc
     set omnifunc=Omni_test