schemas/gen: exclude delphix-integrations/delphix

[radeksimko]

This is to address the fact delphix-integrations/delphix only has pre-releases at the moment, resulting in init failures:

Error: Failed to query available provider packages

Could not retrieve the list of available versions for provider
delphix-integrations/delphix: no available releases match the given
constraints 

[github-actions]

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