ci: Move "MSan" from Cirrus to GitHub Actions

.github/workflows/ci.yml

@@ -488,6 +488,65 @@ jobs:
         run: env
         if: ${{ always() }}
 
+  msan_debian:
+    name: "MSan"
+    runs-on: ubuntu-latest
+    needs: docker_cache
+
+    strategy:
+      fail-fast: false
+      matrix:
+        configuration:
+          - env_vars:
+              CFLAGS: '-fsanitize=memory -g'
+          - env_vars:
+              ECMULTGENPRECISION: 2
+              ECMULTWINDOW: 2
+              CFLAGS: '-fsanitize=memory -g -O3'
+
+    env:
+      ECDH: 'yes'
+      RECOVERY: 'yes'
+      SCHNORRSIG: 'yes'
+      ELLSWIFT: 'yes'
+      CTIMETESTS: 'yes'
+      CC: 'clang'
+      SECP256K1_TEST_ITERS: 32
+      ASM: 'no'
+      WITH_VALGRIND: 'no'
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: CI script
+        env: ${{ matrix.configuration.env_vars }}
+        uses: ./.github/actions/run-in-docker-action
+        with:
+          dockerfile: ./ci/linux-debian.Dockerfile
+          tag: linux-debian-image
+          command: >
+            git config --global --add safe.directory ${{ github.workspace }} &&
+            ./ci/ci.sh
+
+      - run: cat tests.log || true
+        if: ${{ always() }}
+      - run: cat noverify_tests.log || true
+        if: ${{ always() }}
+      - run: cat exhaustive_tests.log || true
+        if: ${{ always() }}
+      - run: cat ctime_tests.log || true
+        if: ${{ always() }}
+      - run: cat bench.log || true
+        if: ${{ always() }}
+      - run: cat config.log || true
+        if: ${{ always() }}
+      - run: cat test_env.log || true
+        if: ${{ always() }}
+      - name: CI env
+        run: env
+        if: ${{ always() }}
+
   mingw_debian:
     name: ${{ matrix.configuration.job_name }}
     runs-on: ubuntu-latest