Fix various log_group / stream_name warnings in tests

[tomkins]

Was trying to fix another issue, but noticed a few easy wins for updating the tests to emit fewer warnings, mostly due to:

watchtower/watchtower/__init__.py

Lines 216 to 225 in 616ec96

	if log_group is not None:
	if log_group_name != __name__:
	raise WatchtowerError("Both log_group_name and deprecated log_group parameter specified")
	warnings.warn("Please use log_group_name instead of log_group", DeprecationWarning)
	self.log_group_name = log_group
	if stream_name is not None:
	if log_stream_name != DEFAULT_LOG_STREAM_NAME:
	raise WatchtowerError("Both log_stream_name and deprecated stream_name parameter specified")
	warnings.warn("Please use log_stream_name instead of stream_name", DeprecationWarning)
	self.log_stream_name = stream_name