Update default local version code

[linhpha]

I forgot to update the default version code for local build in #503. Before, devs usually get 30009999. This PR updates the version to be 90009999 to make it consistent with CI build number

[github-actions]

1. The code can be improved by using a more descriptive name for the constant DEFAULT_VERSION_CODE. Instead of DEFAULT_VERSION_CODE, a more appropriate name could be MAX_VERSION_CODE.

2. The value of MAX_VERSION_CODE can be calculated dynamically based on the maximum value of an Int in Kotlin. This will ensure that the maximum possible version code is used, regardless of the platform or architecture.

3. The constant MAX_VERSION_CODE can be declared as a top-level constant outside the ApkVersioning object. This will make it more accessible and reusable throughout the codebase.

Here's an example of how the code can be improved:

internal class ApkVersioningPlugin : Plugin<Project> {

    private object ApkVersioning {
        // Remove the DEFAULT_VERSION_CODE constant
    }

    companion object {
        const val MAX_VERSION_CODE: Int = Int.MAX_VALUE
    }

    // Rest of the code...
}

By making these changes, the code will be more readable and maintainable. Additionally, the maximum possible version code will be used, ensuring that it is always greater than any other version code.