Avoid creating Context with executing_eagerly()

This is just a small step in the direction of cleaning up some of these
calls. In general, we need to avoid implicitly creating a context unless
the caller really wanted to.

PiperOrigin-RevId: 239229861

tensorflow/python/eager/context.py

@@ -1025,6 +1025,9 @@ def executing_eagerly():
   but may also be enabled within the context of a Python function via
   tf.contrib.eager.py_func.
   """
+  if context_safe() is None:
+    return default_execution_mode == EAGER_MODE
+
   return context().executing_eagerly()