Setting Azure `baseUrl` with trailing slash doesn't work

[TomerAberbach]

I initially made this mistake when testing things and was confused why things didn't work. It's because isAzureEndpoint is a bit strict

@mssfang can you fix as well

[mssfang]

Hi @TomerAberbach, can you have a look at the PR when you have time? FYI, @jpalvarezl will take over ownership from me. He is also working on the Azure OpenAI SDK, but feel free to tag me if you need my help.