Allow bypassing interface translation updates during site installation via an environment variable

Problem/Motivation

When installing Drupal sites with multiple enabled modules and languages (especially in automated CI/CD pipelines, local development environments, or test suites), the translation import and download phases consume a significant amount of time and resources.
In automated testing environments, interface translations are rarely needed, yet the installation process spends considerable time downloading and importing translation files through install_download_translation() and install_finish_translations(). This severely slows down test execution and local development iteration cycles.

Steps to reproduce

Proposed resolution

Introduce an environment variable (e.g., DRUPAL_SKIP_INSTALL_TRANSLATIONS or similar standard configuration) that allows developers and CI environments to bypass the interface translation step during site installation.
Specifically:

• In install_download_translation(), return early if the environment variable is set/active.
• In install_finish_translations(), return an empty array [] when the flag is set, signaling that no translation batch processing is required.

Remaining tasks

Create the Mr

User interface changes

None

Introduced terminology

API changes

None. Introduce support for an environment variable during the installation phase.

Data model changes

None

Release notes snippet