Update "Local development for Prisma Accelerate" for Prisma 7

[ryanburns23]

This doc is out of date for Prisma v7.

When testing, I found that passing a local database string to accelerateUrl causes the error:

Unhandled Rejection: Error [InvalidDatasourceError]: Error validating accelerateUrl: the URL must start with the protocol prisma:// or prisma+postgres://

This makes it difficult to test edge functionality locally. A workaround is to use @prisma/adapter-pg only in local development and accelerateUrl in prod.

https://github.com/prisma/docs/blob/main/content/300-accelerate/580-local-development.mdx