Run Complement tests with MAS in GitHub Actions

Add a 'workers + Postgres + MAS' matrix entry to the complement test
workflow. When the `mas: true` matrix flag is set, the MAS=1 environment
variable is passed to complement.sh, enabling the full MAS integration
(stack: Synapse workers, MAS compat layer, registration shim) to be
exercised in CI.

Author: reivilibre

.github/workflows/complement_tests.yml

@@ -37,6 +37,10 @@ jobs:
           - arrangement: workers
             database: Postgres
 
+          - arrangement: workers
+            database: Postgres
+            mas: true
+
     steps:
       - name: Checkout synapse codebase
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -103,6 +107,7 @@ jobs:
         env:
           POSTGRES: ${{ (matrix.database == 'Postgres') && 1 || '' }}
           WORKERS: ${{ (matrix.arrangement == 'workers') && 1 || '' }}
+          MAS: ${{ (matrix.mas == true) && 1 || '' }}
 
       - name: Formatted sanity check Complement test logs
         # Always run this step if we attempted to run the Complement tests.
@@ -132,6 +137,7 @@ jobs:
         env:
           POSTGRES: ${{ (matrix.database == 'Postgres') && 1 || '' }}
           WORKERS: ${{ (matrix.arrangement == 'workers') && 1 || '' }}
+          MAS: ${{ (matrix.mas == true) && 1 || '' }}
           TEST_ONLY_IGNORE_POETRY_LOCKFILE: ${{ inputs.use_latest_deps && 1 || '' }}
           TEST_ONLY_SKIP_DEP_HASH_VERIFICATION: ${{ inputs.use_twisted_trunk  && 1 || '' }}
 
@@ -162,6 +168,7 @@ jobs:
         env:
           POSTGRES: ${{ (matrix.database == 'Postgres') && 1 || '' }}
           WORKERS: ${{ (matrix.arrangement == 'workers') && 1 || '' }}
+          MAS: ${{ (matrix.mas == true) && 1 || '' }}
           TEST_ONLY_IGNORE_POETRY_LOCKFILE: ${{ inputs.use_latest_deps && 1 || '' }}
           TEST_ONLY_SKIP_DEP_HASH_VERIFICATION: ${{ inputs.use_twisted_trunk  && 1 || '' }}