Make test ordering and parametrization reproducible (quantumlib#4788)

Implement deterministic ordering of pytest parameters.
Add CIRQ_TESTING_RANDOM_SEED environment variable for seeding
random numbers generation in random and numpy.random modules.
Use commit epoch time as the default seed to have a non-constant,
but deterministic seeding.

NB: Use empty CIRQ_TESTING_RANDOM_SEED to prevent seeding, for example,
    CIRQ_TESTING_RANDOM_SEED="" check/pytest

This implements quantumlib#4787

cirq/contrib/acquaintance/gates_test.py

@@ -17,7 +17,7 @@
 from string import ascii_lowercase as alphabet
 from typing import Optional, Sequence, Tuple
 
-import numpy as np
+import numpy
 import pytest
 
 import cirq
@@ -232,9 +232,8 @@ def test_swap_network_init_error():
         cca.SwapNetworkGate((3,))
 
 
-rng = np.random.default_rng()
 part_lens_and_acquaintance_sizes = [
-    [[l + 1 for l in rng.poisson(size=n_parts, lam=lam)], rng.poisson(4)]
+    [[l + 1 for l in numpy.random.poisson(size=n_parts, lam=lam)], numpy.random.poisson(4)]
     for n_parts, lam in product(range(2, 20, 3), range(1, 4))
 ]
 

cirq/ops/common_gates_test.py

@@ -1042,10 +1042,10 @@ def test_ixyz_circuit_diagram():
 @pytest.mark.parametrize(
     'theta,exp',
     [
-        {sympy.Symbol("theta"), 1 / 2},
-        {np.pi / 2, 1 / 2},
-        {np.pi / 2, sympy.Symbol("exp")},
-        {sympy.Symbol("theta"), sympy.Symbol("exp")},
+        (sympy.Symbol("theta"), 1 / 2),
+        (np.pi / 2, 1 / 2),
+        (np.pi / 2, sympy.Symbol("exp")),
+        (sympy.Symbol("theta"), sympy.Symbol("exp")),
     ],
 )
 def test_rxyz_exponent(theta, exp):

cirq/protocols/json_serialization_test.py

@@ -537,11 +537,14 @@ def _list_public_classes_for_tested_modules():
     # to remove DeprecationWarning noise during test collection
     with warnings.catch_warnings():
         warnings.simplefilter("ignore")
-        return [
-            (mod_spec, o, n)
-            for mod_spec in MODULE_TEST_SPECS
-            for (o, n) in mod_spec.find_classes_that_should_serialize()
-        ]
+        return sorted(
+            (
+                (mod_spec, n, o)
+                for mod_spec in MODULE_TEST_SPECS
+                for (n, o) in mod_spec.find_classes_that_should_serialize()
+            ),
+            key=lambda mno: (str(mno[0]), mno[1]),
+        )
 
 
 @pytest.mark.parametrize(