Remove deprecated stratify module (quantumlib#5714)

- This was just a pointer from optimizers so a simple removal.

Author: dstrain115

cirq/optimizers/__init__.py

@@ -42,8 +42,6 @@
 
 from cirq.optimizers.synchronize_terminal_measurements import SynchronizeTerminalMeasurements
 
-from cirq.transformers.stratify import stratified_circuit
-
 from cirq.transformers.analytical_decompositions import (
     compute_cphase_exponents_for_fsim_decomposition,
     decompose_cphase_into_two_fsim,
@@ -132,11 +130,3 @@
     deadline="v0.16",
     create_attribute=True,
 )
-
-_compat.deprecated_submodule(
-    new_module_name="cirq.transformers.stratify",
-    old_parent="cirq.optimizers",
-    old_child="stratify",
-    deadline="v0.16",
-    create_attribute=True,
-)

cirq/transformers/stratify_test.py

@@ -16,11 +16,6 @@
 import cirq
 
 
-def test_deprecated_submodule():
-    with cirq.testing.assert_deprecated("Use cirq.transformers.stratify instead", deadline="v0.16"):
-        _ = cirq.optimizers.stratify.stratified_circuit
-
-
 def test_stratified_circuit_classifier_types():
     a, b, c, d = cirq.LineQubit.range(4)