.github/workflows: Keep scst_user fork coverage manual

Reserve the legacy-kernel fork checks for manual runs instead of adding
two VM jobs and extra kernel builds to the regular CI selection. Remove
the Linux 5.8/5.9 Ginkgo jobs and regression matrix entries, retaining the
kernel pins and local-only VM runner for reproduction.

Label the fork spec manual and exclude that label from both ci-pr and
ci-push. Move smoke to the READ CAPACITY entries so their existing CI
coverage remains intact. Keep full manual runs inclusive, update the
selection checks, and document focused manual execution.

.github/kernel-matrix.conf

@@ -23,8 +23,6 @@ GITHUB_REGRESSION_KERNEL_SELECTORS="\
 6.1 \
 5.15 \
 5.10 \
-5.9 \
-5.8 \
 5.4 \
 4.19 \
 4.14 \

.github/workflows/ginkgo.yml

@@ -66,63 +66,3 @@ jobs:
             ${{ runner.temp }}/ginkgo-image/*.json
             ${{ runner.temp }}/ginkgo-image/*.txt
             ${{ runner.temp }}/ginkgo-results/
-
-  user-kernels:
-    # Run the local scst_user specs on both sides of the Linux 5.9 boundary of
-    # dev_user_map_buf(). Named like the regression jobs; the build step checks
-    # each name against its scripts/ci/<pin>.env.
-    name: ${{ matrix.name }}
-    runs-on: ubuntu-24.04
-    timeout-minutes: 120
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          - pin: kernel-5.8
-            name: 5.8.18-300.fc33^Fedora^33
-          - pin: kernel-5.9
-            name: 5.9.16-200.fc33^Fedora^33
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          persist-credentials: false
-          fetch-depth: 0
-      - name: Select Ginkgo checks
-        id: changes
-        env:
-          BASE_SHA: ${{ github.event.pull_request.base.sha }}
-          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-        run: |
-          python3 scripts/ci/select_checks.py --check ginkgo --event "$GITHUB_EVENT_NAME" \
-            --base "$BASE_SHA" --head "$HEAD_SHA"
-      - name: Install build and VM tools
-        if: steps.changes.outputs.run == 'true'
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y qemu-system-x86 qemu-utils openssh-client e2fsprogs fakeroot
-      - name: Build SCST image with the kernel from scripts/ci/${{ matrix.pin }}.env
-        if: steps.changes.outputs.run == 'true'
-        timeout-minutes: 60
-        env:
-          PIN: ${{ matrix.pin }}
-          NAME: ${{ matrix.name }}
-        run: |
-          source "scripts/ci/$PIN.env"
-          [[ $NAME == "$KERNEL_BUILD^"* ]] || { echo "::error::$NAME does not match $PIN.env"; exit 1; }
-          bash scripts/ci/build-image ginkgo "$RUNNER_TEMP/ginkgo-image" "$PIN"
-      - name: Run local scst_user tests against the compiled SCST
-        if: steps.changes.outputs.run == 'true'
-        run: |
-          python3 scripts/ci/vm.py ginkgo "$RUNNER_TEMP/ginkgo-image" \
-            "$RUNNER_TEMP/ginkgo-results" --timeout 3000 --local-only --ginkgo-label user
-      - name: Save build logs, reports and serial console
-        if: always() && steps.changes.outputs.run == 'true'
-        uses: actions/upload-artifact@v4
-        with:
-          name: ginkgo-${{ matrix.pin }}-results
-          retention-days: 7
-          path: |
-            ${{ runner.temp }}/ginkgo-image/*.log
-            ${{ runner.temp }}/ginkgo-image/*.json
-            ${{ runner.temp }}/ginkgo-image/*.txt
-            ${{ runner.temp }}/ginkgo-results/