[Storage] Nightly pipeline failing on PublishDocsToNightlyBranch, likely due to extensions

[jalauzon-msft]

Since we introduced the new azure-storage-extensions package into main which contains only a c-extension, the docs step of the nightly pipeline has been failing. I don't think we will be able to generate docs for this type of package so disabling it for now is a fine solution to get the pipeline to pass.

Example (can also just look at Storage nightly runs):
https://dev.azure.com/azure-sdk/internal/_build/results?buildId=3461703&view=logs&j=f8e040b3-c0ff-5789-0eda-99daaaa3fc1b&t=bf282306-23d8-55b2-36ef-08e066152d1f

[scbedd]

This package doesn't currently support the sphinx environment (EG building docs), so we need to just skip validating this package on docs.

[scbedd]

@danieljurek @JimSuplizio I dug around the CI a bit to find the exclusion methodology. See #34137