revert some behavior

src/_nebari/stages/infrastructure/__init__.py

@@ -618,21 +618,19 @@ def check_provider(cls, data: Any) -> Any:
                 raise ValueError(
                     f"'{provider}' is not a valid enumeration member; permitted: local, existing, aws, gcp, azure"
                 )
-
-        set_providers = [
-            provider
-            for provider in provider_name_abbreviation_map.keys()
-            if provider in data and data[provider]
-        ]
-        num_providers = len(set_providers)
-        if num_providers > 1:
-            raise ValueError(
-                f"Only a single provider may be set.  Multiple providers are set: {set_providers}"
-            )
-        elif num_providers == 1:
-            data["provider"] = provider_name_abbreviation_map[set_providers[0]]
-        elif num_providers == 0:
-            data["provider"] = schema.ProviderEnum.local.value
+        else:
+            set_providers = [
+                provider
+                for provider in provider_name_abbreviation_map.keys()
+                if provider in data
+            ]
+            num_providers = len(set_providers)
+            if num_providers > 1:
+                raise ValueError(f"Multiple providers set: {set_providers}")
+            elif num_providers == 1:
+                data["provider"] = provider_name_abbreviation_map[set_providers[0]]
+            elif num_providers == 0:
+                data["provider"] = schema.ProviderEnum.local.value
 
         return data