The change updates the imports to use simplejson library and
monasca_api.common.rest instead of monasca_common.rest, since
it was moved to this project during the API's merge.
Temporarily set following jobs as non-voting:
* monasca-tempest-python3-influxdb
* build-monasca-docker-image
* publish-monasca-api-docker-image
Change-Id: Ife3d2c9795a9dc406c2927cc9a077dda01c183c6
Story: 2007549
Task: 39389