Adapt MySQL Admin Checks to new release model

With Oracle's introduction of Long Term Support (LTS) and Innovation
releases in 2023 1, the logic implemented in check_database_inc.php
for the old General Availability (GA) model is no longer applicable.

This commit adapts the logic as follows:

• releases <= 8.0 use the former model with a GA version marking
  start of official support, 5 years active + 3 years extended)
  after which the release is considered end-of-life
• LTS releases basically follow the same model, but the GA version
  is always the .0 (8.4.0 is the first LTS release)
• Innovation releases support ends when the next version is released,
  or 3 months after go-live if the next release is not defined

Fixes 0034480