Allow ops_test.py to run with the api folder collapsed at the root. (#21360)

Which is the setup in the wheel file.

Author: hertschuh

keras/src/ops/ops_test.py

@@ -2,7 +2,11 @@
 
 from absl.testing import parameterized
 
-from keras.api import ops as api_ops_root
+try:
+    from keras.api import ops as api_ops_root
+except ImportError:
+    from keras import ops as api_ops_root
+
 from keras.src import backend
 from keras.src import ops
 from keras.src import testing