Syncing Connection and ConnectionString fix the bug that AdminDatabase Setting is invalid when DataSource is setted.

[tianvan]

When both Connection and ConnectionString are not null, Connection's ConnectionString is different to ConnectionString, the ConnectionString will be used instead of the Connection's ConnectionString.

It will cause a bug, for example, I need to create database through following code:

DbContext.Database.Migrate()

if DatabaseSource is Setted:

extension.WithDataSource(dataSource);

then we set AdminDatabase:

extension.WithAdminDatabase("postgres");

it wont work.