[BUGFIX] Update default base url for cloud API

[jcampbell]

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Legend

[Kilo59]

~I moved renamed DEFAULT_BASE_URL -> CLOUD_BASE_URL and move it to the core/http.py~

An alternative would be to create a ~great_expectations/constants.py~ or great_expectations/data_context/cloud_constants.py file.

https://github.com/great-expectations/great_expectations/pull/6176/commits/5374b7a19f615d6a25396be8acd56a0d0c834553