ci: split functionaltest-lua into two separate jobs (#22201)

More specifically, move the job testing the oldest supported cmake into
its own job. This opens the way for other jobs to use powerful and
advanced cmake features such as choosing which files to use with the -S
flag.

Removed testing from this job as this probably won't reveal anything
that other jobs already doesn't already show, since the only difference
is the cmake version.

.github/workflows/ci.yml

@@ -194,15 +194,11 @@ jobs:
 
             # functionaltest-lua is our dumping ground for non-mainline configurations.
             # 1. Check that the tests pass with PUC Lua instead of LuaJIT.
-            # 2. Use as oldest/minimum versions of dependencies/build tools we
+            # 2. No treesitter parsers installed.
-            #    still explicitly support so we don't accidentally rely on
-            #    features that is only available on later versions.
-            # 3. No treesitter parsers installed.
           - flavor: functionaltest-lua
             cc: gcc
             runner: ubuntu-22.04
             os: linux
-            cmake: minimum_required
     runs-on: ${{ matrix.runner }}
     timeout-minutes: 45
     env:
@@ -218,24 +214,6 @@ jobs:
         if: matrix.os == 'linux'
         run: ./.github/scripts/install_deps_ubuntu.sh
 
-      - name: Install minimum required version of cmake
-        if: matrix.cmake == 'minimum_required'
-        env:
-          CMAKE_URL: 'https://cmake.org/files/v3.10/cmake-3.10.0-Linux-x86_64.sh'
-          CMAKE_VERSION: '3.10.0'
-        shell: bash
-        run: |
-          curl --retry 5 --silent --show-error --fail -o /tmp/cmake-installer.sh "$CMAKE_URL"
-          mkdir -p "$HOME/.local/bin" /opt/cmake-custom
-          chmod a+x /tmp/cmake-installer.sh
-          /tmp/cmake-installer.sh --prefix=/opt/cmake-custom --skip-license
-          ln -sfn /opt/cmake-custom/bin/cmake "$HOME/.local/bin/cmake"
-          cmake_version="$(cmake --version | head -1)"
-          echo "$cmake_version" | grep -qF "cmake version $CMAKE_VERSION" || {
-            echo "Unexpected CMake version: $cmake_version"
-            exit 1
-          }
-
       - name: Install brew packages
         if: matrix.os == 'osx'
         run: |
@@ -276,6 +254,47 @@ jobs:
         name: Install nvim
         run: ./ci/run_tests.sh install_nvim
 
+  old_cmake:
+    name: Test oldest supported cmake
+    runs-on: ubuntu-22.04
+    timeout-minutes: 15
+    env:
+      CI_OS_NAME: linux
+      CMAKE_URL: 'https://cmake.org/files/v3.10/cmake-3.10.0-Linux-x86_64.sh'
+      CMAKE_VERSION: '3.10.0'
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Setup common environment variables
+        run: ./.github/workflows/env.sh old_cmake
+
+      - name: Install apt packages
+        run: ./.github/scripts/install_deps_ubuntu.sh
+
+      - name: Install minimum required version of cmake
+        run: |
+          curl --retry 5 --silent --show-error --fail -o /tmp/cmake-installer.sh "$CMAKE_URL"
+          mkdir -p "$HOME/.local/bin" /opt/cmake-custom
+          chmod a+x /tmp/cmake-installer.sh
+          /tmp/cmake-installer.sh --prefix=/opt/cmake-custom --skip-license
+          ln -sfn /opt/cmake-custom/bin/cmake "$HOME/.local/bin/cmake"
+          cmake_version="$(cmake --version | head -1)"
+          echo "$cmake_version" | grep -qF "cmake version $CMAKE_VERSION" || {
+            echo "Unexpected CMake version: $cmake_version"
+            exit 1
+          }
+
+      - uses: ./.github/actions/cache
+
+      - name: Build dependencies
+        run: make deps
+
+      - name: Build
+        run: make CMAKE_FLAGS="-D CI_BUILD=ON -D CMAKE_INSTALL_PREFIX:PATH=$INSTALL_PREFIX -D MIN_LOG_LEVEL=3"
+
+      - name: Install
+        run: make install
+
   windows:
     runs-on: windows-2019
     timeout-minutes: 45