Deletion of CosmosDB Database isn't working

## Describe the bug
I'm trying to delete a MongoDB on a CosmosDB Serverless instance, but the deletion failed. No error message will be displayed.

**Command Name**
`az cosmosdb mongodb database delete`

**Errors:**

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.
1. Create a CosmosDB Serverless account of type MongoDB
2. Create a database in the new CosmosDB Account (I used Azure Cli)
3. Try to delete the new created database:
`az cosmosdb mongodb database delete --account-name {} --name {} --resource-group {} --subscription {} --yes`

## Expected Behavior

Database will be removed

## Environment Summary
```
macOS-10.15.7-x86_64-i386-64bit
Python 3.8.7
Installer: HOMEBREW

azure-cli 2.18.0 *