patch 8.1.1826: tests use hand coded feature and option checks

Problem:    Tests use hand coded feature and option checks.
Solution:   Use the commands from check.vim in more tests.

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1826,
 /**/
     1825,
 /**/