Remove file-based seeding for Cosmos DB functional tests (#38005)

Author: JoasE

test/EFCore.Cosmos.FunctionalTests/EFCore.Cosmos.FunctionalTests.csproj

@@ -51,9 +51,6 @@
     <None Update="cosmosConfig.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
-    <None Update="Northwind.json">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-    </None>
   </ItemGroup>
 
   <ItemGroup>