Azure Key Vault Certificates client library samples for JavaScript

[KeyVault] Running samples on CI (#6845)

I had to re-record some of the tests because I was being impacted by the intermittent bug described in #6440 , the issue happened to be a badly named property in the affected the tests, which caused the resources to lost their uniqueness (I was referring to the suffix property as "certificateSuffix" instead of just "suffix"), so:

I also had to repeat the "Matrix" section of the main template in each tests.yml since I'm adding a step for samples. We'll clean this up later.

Fixes #6440