add fixes for flaky tests (#5146)

While working on tendermint my colleague @jinmannwong fixed a few of the unit tests that we found to be flaky in our CI. We thought that you might find this useful, see below for comments.

libs/timer/throttle_timer_test.go

@@ -67,14 +67,16 @@ func TestThrottle(test *testing.T) {
 	time.Sleep(longwait)
 	assert.Equal(2, c.Count())
 
-	// send 12, over 2 delay sections, adds 3
+	// send 12, over 2 delay sections, adds 3 or more. It
+	// is possible for more to be added if the overhead
+	// in executing the loop is large
 	short := time.Duration(ms/5) * time.Millisecond
 	for i := 0; i < 13; i++ {
 		t.Set()
 		time.Sleep(short)
 	}
 	time.Sleep(longwait)
-	assert.Equal(5, c.Count())
+	assert.LessOrEqual(5, c.Count())
 
 	close(t.Ch)
 }