patch 9.1.2108: tests: Test_foldtextresult_rightleft() does not restore 'columns'

Problem:  Test_foldtextresult_rightleft() does not restore 'columns'
          (after v9.1.2102)
Solution: Save and restore the value of 'columns' (zeertzjq).

related: #19220
closes:  #19234

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_fold.vim

@@ -1504,6 +1504,7 @@ endfunc
 func Test_foldtextresult_rightleft()
   CheckFeature rightleft
 
+  let save_columns = &columns
   new
   set columns=70
   setlocal rightleft
@@ -1519,6 +1520,7 @@ func Test_foldtextresult_rightleft()
   call assert_equal('+--  2 lines: ' .. multibyte, foldtextresult(1))
 
   bw!
+  let &columns = save_columns
 endfunc
 
 " Test for merging two recursive folds when an intermediate line with no fold

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2108,
 /**/
     2107,
 /**/