message: Add decorator to run all tests in a class in deprecated graph mode.
  Separated out change in core from cl/266279053
diff: @@ -1226,6 +1226,19 @@ def deprecated_graph_mode_only(func=None):
  run_deprecated_v1 = deprecated_graph_mode_only
  +def run_all_in_deprecated_graph_mode_only(cls):
  + """Execute all tests in a class in graph mode."""
  + base_decorator = deprecated_graph_mode_only
  + for name in dir(cls):
  + if (not name.startswith(unittest.TestLoader.testMethodPrefix) or
  + name == "test_session"):
  + continue
  + value = getattr(cls, name, None)
  + if callable(value):
  + setattr(cls, name, base_decorator(value))
  + return cls
  +
  +
  def run_v1_only(reason, func=None):
  """Execute the decorated test only if running in v1 mode.
  