patch 8.0.1365: when one channel test fails others fail as well

Problem:    When one channel test fails others fail as well.
Solution:   Stop the job after a failure.  Also add a couple of tests to the
            list of flaky tests.
diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index c953d6d..8a4a9b7 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -251,6 +251,7 @@
       \ 'Test_exit_callback_interval()',
       \ 'Test_nb_basic()',
       \ 'Test_oneshot()',
+      \ 'Test_paused()',
       \ 'Test_pipe_through_sort_all()',
       \ 'Test_pipe_through_sort_some()',
       \ 'Test_quoteplus()',
@@ -259,6 +260,7 @@
       \ 'Test_terminal_composing_unicode()',
       \ 'Test_terminal_noblock()',
       \ 'Test_terminal_redir_file()',
+      \ 'Test_terminal_tmap()',
       \ 'Test_with_partial_callback()',
       \ ]