ci: fix flaky tracer tests (#10436)

Previous PR fixed flakiness in one part of this test, but there is a
remaining bit which is also flaky.

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tests/tracer/test_rate_limiter.py

@@ -179,8 +179,8 @@ def test_rate_limiter_effective_rate_starting_rate(time_window):
         assert limiter.current_window_ns == (now_ns + time_window)
         assert limiter.prev_window_rate == 0.5
 
-    # Gap of 1.9999 seconds, same window
-    time_ns = now_ns + (1.9999 * time_window)
+    # Gap of 1.85 seconds, same window
+    time_ns = now_ns + (1.85 * time_window)
     with mock.patch("ddtrace.internal.rate_limiter.compat.monotonic_ns", return_value=time_ns):
         assert limiter.is_allowed() is False
         assert limiter.effective_rate == 0.5