Replace and deprecate _install_get_version_info()

Problem/Motivation

Discovered in 🐛 Composer tests fail because of invalid Drupal version Fixed we are maintaining a complex regex that can parse a full version number in _install_get_version_info() but that is only used in three places in core, once in the installer and also in two tests, and even then only to get the major/minor version number.

Steps to reproduce

Proposed resolution

Replace _install_get_version_info() with explode() or similar.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet