Fix raise condition in testCloudantAction.js.

[falkzoll]

• The cloudant test action (testCloudantAction.js) sometimes failed with 404 (Object Not Found) since getDocument was started while putDocument was not completed, yet.
• Also remove nodejs:8 support from this action.
• Also do the delete database at action start for nodejs:16 and nodejs:20, too, to make it more stable in handling errors during action execution.