Add necessary query params to POSTGRES_PRISMA_URL for Vercel integration

When integrating with Vercel, Supabase automatically adds environment variables to Vercel, however, certain params like `pgBouncer=true` and `connection_limit=1` are not automatically added. This leads to some confusing debugging and the only place I can see these being documented is on the [Prisma integration page](https://supabase.com/partners/integrations/prisma). Seems like if these params are necessary for an application to work correctly, they should just be added automatically. Its not entirely clear to me why other params _are_ added, like `sslmode=require` and `supa=base-pooler.x` (though that could be a separate issue), but at least having everything I need in one place would be a good single source of truth.