Update CORE_LEG_STABLE to 7.99

Migrated issue

Reported by: poker10

Related to !97 (merged) !95 (merged)

Problem/Motivation

Drupal 7.99 was released on 6.12.2023. We should update the CORE_LEG_STABLE variable.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes