CI: Move the nightly Lagom GCC CI to GitHub actions

.github/workflows/ci.yml

@@ -51,6 +51,7 @@ jobs:
 
     uses: ./.github/workflows/lagom-template.yml
     with:
+      toolchain: 'Clang'
       os_name: ${{ matrix.os_name }}
       os: ${{ matrix.os }}
       fuzzer: ${{ matrix.fuzzer }}

.github/workflows/lagom-template.yml

@@ -3,6 +3,9 @@ name: Lagom Template
 on:
   workflow_call:
     inputs:
+        toolchain:
+          required: true
+          type: string
         os_name:
           required: true
           type: string
@@ -50,6 +53,7 @@ jobs:
         with:
           os: ${{ inputs.os_name }}
           arch: 'Lagom'
+          toolchain: ${{ inputs.toolchain }}
           cache_key_extra: ${{ inputs.fuzzer }}
           serenity_ccache_path: ${{ env.CCACHE_DIR }}
           download_cache_path: ${{ github.workspace }}/Build/caches
@@ -58,8 +62,13 @@ jobs:
         id: 'build-parameters'
         run: |
           if ${{ inputs.os_name == 'Linux' }} ; then
-            echo "host_cc=clang-18" >> "$GITHUB_OUTPUT"
-            echo "host_cxx=clang++-18" >> "$GITHUB_OUTPUT"
+            if ${{ inputs.toolchain == 'Clang' }} ; then
+              echo "host_cc=clang-18" >> "$GITHUB_OUTPUT"
+              echo "host_cxx=clang++-18" >> "$GITHUB_OUTPUT"
+            elif ${{ inputs.toolchain == 'GNU' }} ; then
+              echo "host_cc=gcc-13" >> "$GITHUB_OUTPUT"
+              echo "host_cxx=g++-13" >> "$GITHUB_OUTPUT"
+            fi
           elif ${{ inputs.os_name == 'macOS' }} ; then
             echo "host_cc=$(brew --prefix llvm@18)/bin/clang" >> "$GITHUB_OUTPUT"
             echo "host_cxx=$(brew --prefix llvm@18)/bin/clang++" >> "$GITHUB_OUTPUT"

.github/workflows/nightly.yml

@@ -22,3 +22,15 @@ jobs:
       os: ubuntu-22.04
       arch: 'x86_64'
       coverage: 'ON'
+
+  LagomGCC:
+    if: always() && github.repository == 'SerenityOS/serenity' && github.ref == 'refs/heads/master'
+
+    strategy:
+      fail-fast: false
+
+    uses: ./.github/workflows/lagom-template.yml
+    with:
+      toolchain: 'GNU'
+      os_name: 'Linux'
+      os: ubuntu-22.04

Meta/Azure/nightly-pipeline.yml

@@ -18,13 +18,3 @@ stages:
       - template: Lagom.yml
         parameters:
           os: 'Android'
-
-  - stage: Lagom_GCC
-    dependsOn: []
-    jobs:
-      - template: Lagom.yml
-        parameters:
-          os: 'Linux'
-          fuzzer: 'NoFuzz'
-          host_cc: 'gcc-13'
-          host_cxx: 'g++-13'