[Tune][CI] Skip zoopt invalid values test (#31419)

Skips a zoopt searcher test that's causing the `test_searchers` suite in CI to be flaky. Skipping as this is not a Tune issue and needs to be fixed in the zoopt library.

I re-enabled this test in #31147 since I thought that nan/inf error handling had been fixed in a recent zoopt release. However, nan/inf values will still cause an error if reported on trial complete.

This test should be enabled after polixir/ZOOpt#7 is included in the next zoopt release.

Signed-off-by: Justin Yu <[email protected]>

python/ray/tune/tests/test_searchers.py

@@ -327,18 +327,24 @@ def testSkopt(self):
         self.assertCorrectExperimentOutput(out)
 
     def testZOOpt(self):
+        self.skipTest(
+            "Recent ZOOpt versions fail handling invalid values gracefully. "
+            "Skipping until a fix is added in a future ZOOpt release."
+        )
         from ray.tune.search.zoopt import ZOOptSearch
 
-        np.random.seed(1000)  # At least one nan, inf, -inf and float
+        # This seed tests that a nan result doesn't cause an error if it shows
+        # up after the initial data collection phase.
+        np.random.seed(1002)  # At least one nan, inf, -inf and float
 
         with self.check_searcher_checkpoint_errors_scope():
             out = tune.run(
                 _invalid_objective,
-                search_alg=ZOOptSearch(budget=100, parallel_num=4),
+                search_alg=ZOOptSearch(budget=25, parallel_num=4),
                 config=self.config,
                 metric="_metric",
                 mode="max",
-                num_samples=8,
+                num_samples=16,
                 reuse_actors=False,
             )
         self.assertCorrectExperimentOutput(out)