Fix and enhance Azurite and fakegcs emulator support

[shreyas-s-rao]

How to categorize this issue?

/kind enhancement

What would you like to be added

1. Azurite support is currently broken, due to a recent change in Stop using *_STORAGE_API_ENDPOINT environment variables #759 to use domain instead of storageAPIEndpoint to specify custom URL for Azure backends. It is necessary to switch to production-style URLs for Azurite, in order to make use of this new domain field.
2. The field AZURE_EMULATOR_ENABLED should be removed. Currently this field only helps in determining whether the URL should use http or https scheme when building the Azure custom URL, and is only used for supporting Azurite. Going forward, Azurite should also use https endpoints (enabled by creating TLS certs on-the-go via scripts).
3. The field GOOGLE_EMULATOR_ENABLED should also be removed, due to the same reason as above.