Remove incorrect use of uri variable name for a url path

[ohmayr]

Refactor the following piece of code to use an f-string. Currently, it incorrectly names a url path as uri which is confusing:

response = await getattr(self._session, method)(
            "{host}{uri}".format(host=self._host, uri=uri),
            timeout=timeout,
            headers=headers,
            params=rest_helpers.flatten_query_params(query_params),
        )

Do the same for sync code.