patch 8.0.0433: beeps when running tests

Problem:    Quite a few beeps when running tests.
Solution:   Set 'belloff' for these tests. (Christian Brabandt)
diff --git a/src/testdir/test14.in b/src/testdir/test14.in
index fb987eb..3fc39fe 100644
--- a/src/testdir/test14.in
+++ b/src/testdir/test14.in
@@ -6,6 +6,7 @@
 
 STARTTEST
 :so small.vim
+:set belloff=all
 /Start cursor here
 vaBiBD:?Bug?,/Piece/-2w! test.out
 /^- Bug