Rewrite languaged config fails on installations with non-English default language

Problem/Motivation

The module fails on the following scenario:

• Drupal installation with non-English default language (Eg. Spanish)
• Module providing configuration rewrite for that language (Eg. config/rewrite/language/es/system.site.yml)

Steps to reproduce

As described.

Proposed resolution

Apply default language configuration rewrittings on main configuration.

Remaining tasks

Review, test.

User interface changes

N/A

API changes

None.

Data model changes

N/A