[Key Vault Certificates] Add more import tests

[sadasant]

Check other languages for opportunities to add more tests to our clients.

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(Original body of this issue:)

Importing a certificate can be done in several ways. Some of them require sending a password. We should test these cases.

The Python team added some tests that we should also have in TS: https://github.com/Azure/azure-sdk-for-python/blob/2fc1769c31f7b40b58e0fa216220672143cf6dca/sdk/keyvault/azure-keyvault-certificates/tests/test_certificates_client.py#L227

[sadasant]

Pushed this to October.

[sadasant]

Changed the body of the issue and the title to more generally refer to test alignments across languages.

[github-actions]

Hi @sadasant, we deeply appreciate your input into this project. Regrettably, this issue has remained inactive for over 2 years, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.