Revert "add Qt5 compatibility wrapper for addAction and linux-qt5 CI job"

This reverts commit 5e40349768.

.github/workflows/build.yml

@@ -173,33 +173,3 @@ jobs:
           files: Reclass-x86_64.AppImage
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
-  linux-qt5:
-    runs-on: ubuntu-22.04
-
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          submodules: recursive
-
-      - name: Install Qt5
-        uses: jurplel/install-qt-action@v4
-        with:
-          version: '5.15.2'
-          cache: true
-
-      - name: Install dependencies
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y ninja-build libgl1-mesa-dev
-
-      - name: Configure
-        run: cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
-
-      - name: Build
-        run: cmake --build build
-
-      - name: Test
-        run: xvfb-run ctest --test-dir build --output-on-failure --exclude-regex "test_editor"
-        env:
-          QT_QPA_PLATFORM: offscreen