chore(CI): drop checks - only keep latest Ubuntu 24.04 (#18991)

* chore(CI): Nuke 20.04 checks

* revert back to old where we dont test gcc on pch

* only test latest version. Keep it up to date folks

.github/workflows/core-build-pch.yml

@@ -16,30 +16,10 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-20.04
-            compiler:
-              CC: gcc-10
-              CXX: g++-10
-          - os: ubuntu-20.04
-            compiler:
-              CC: clang-12
-              CXX: clang++-12
-          - os: ubuntu-22.04
-            compiler:
-              CC: clang-15
-              CXX: clang++-15
-          - os: ubuntu-22.04
-            compiler:
-              CC: gcc-12
-              CXX: g++-12
           - os: ubuntu-24.04
             compiler:
               CC: clang-18
               CXX: clang++-18
-          - os: ubuntu-24.04
-            compiler:
-              CC: gcc-14
-              CXX: g++-14
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.os }}-${{ matrix.compiler.CC }}-pch
     if: github.repository == 'azerothcore/azerothcore-wotlk' && !github.event.pull_request.draft