chore: remove hardcoded URL validation and related tests
Since we won't have these attributes anymore in Prisma 7, as well as
`env()` in the PSL, this validation is no longer possible.
It's up to users to ensure that they don't hardcode any sensitive
information in `prisma.config.ts`. Perhaps we could provide an ESLint
plugin in the future to help with that.
Ref: https://linear.app/prisma-company/issue/TML-1339/remove-url-directurl-shadowdatabaseurl-datasource-attributes-from-psl
Ref: https://linear.app/prisma-company/issue/TML-1340/remove-env-from-psl