Limit SBMultipass Test to speed 4 to 5

This should help with some test timeout issues.

BUG=aomedia:2774

Change-Id: I398e2c87d89fafd13629f7e599988fd678e932b1
diff --git a/test/sb_multipass_test.cc b/test/sb_multipass_test.cc
index 051a24f..d2f56db 100644
--- a/test/sb_multipass_test.cc
+++ b/test/sb_multipass_test.cc
@@ -147,7 +147,7 @@
 
 TEST_P(AV1SBMultipassTest, TwoPassMatchTest) { DoTest(); }
 
-AV1_INSTANTIATE_TEST_SUITE(AV1SBMultipassTest, ::testing::Range(0, 6),
+AV1_INSTANTIATE_TEST_SUITE(AV1SBMultipassTest, ::testing::Range(4, 6),
                            ::testing::Bool());
 
 }  // namespace