FIX: flaky test exponential generator (apache#14287)

* changing success_percentage test correctness of random exponential generator to 20% to fix its flakiness

* Re-Trigger build

tests/python/unittest/test_random.py

@@ -560,12 +560,12 @@ def test_exponential_generator():
         for scale in [0.1, 1.0]:
             buckets, probs = gen_buckets_probs_with_ppf(lambda x: ss.expon.ppf(x, loc=0, scale=scale), 5)
             generator_mx = lambda x: mx.nd.random.exponential(scale, shape=x, ctx=ctx, dtype=dtype).asnumpy()
-            verify_generator(generator=generator_mx, buckets=buckets, probs=probs)
+            verify_generator(generator=generator_mx, buckets=buckets, probs=probs, success_rate=0.20)
             generator_mx_same_seed = \
                 lambda x: np.concatenate(
                     [mx.nd.random.exponential(scale, shape=x // 10, ctx=ctx, dtype=dtype).asnumpy()
                      for _ in range(10)])
-            verify_generator(generator=generator_mx_same_seed, buckets=buckets, probs=probs)
+            verify_generator(generator=generator_mx_same_seed, buckets=buckets, probs=probs, success_rate=0.20)
 
 @with_seed()
 def test_poisson_generator():