* Implement SetCredentials for MongoDB, adding support for static accounts
* rework SetCredentials to split from CreateUser, and to parse the url for database
* Add integration test for mongodb static account rotation
* check the length of the password results to avoid out-of-bounds
* remove unused method
* use the pre-existing test helper for this. Add parse method to helper
* remove unused command
Merge both functions for creating mongodb containers into one.
Add retries to docker container cleanups.
Require $VAULT_ACC be set to enable AWS tests.
