patch 8.2.1432: various inconsistencies in test files

Problem:    Various inconsistencies in test files.
Solution:   Add modelines where they were missing.  Use Check commands instead
            of silently skipping over tests.  Adjust indents and comments.
            (Ken Takata, closes #6695)
diff --git a/src/testdir/test_terminal2.vim b/src/testdir/test_terminal2.vim
index deeb86f..93ace42 100644
--- a/src/testdir/test_terminal2.vim
+++ b/src/testdir/test_terminal2.vim
@@ -370,9 +370,8 @@
 endfunc
 
 func Test_terminal_does_not_truncate_last_newlines()
-  " This test does not pass through ConPTY.
   if has('conpty')
-    return
+    throw 'Skipped: fail on ConPTY'
   endif
   let contents = [
   \   [ 'One', '', 'X' ],