[Database\Capsule] Only create a "config" instance if only it not yet created.

| Q             | A
| ------------- | ---
| Bug fix?      | yes (I consider it a bug, in my use case :smile:)
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | None
| License       | MIT
| Doc PR        | None

On one of the project I'm working right now, I'm using both `Config` and `Capsule` component, since I register config service location first and then capsule, all the preloaded config is destroy and the config service location is converted to instance of `Illuminate\Support\Fluent` which is not ideal in my use case.

Signed-off-by: crynobone <crynobone@gmail.com>