ci(sync-files): add global code owners

Signed-off-by: M. Fatih Cırıt <mfc@autoware.org>

Author: xmfcx

.github/CODEOWNERS-manual

@@ -1 +0,0 @@
-* mfc@autoware.org ryohsuke.mitsudome@tier4.jp yutaka.kondo@tier4.jp

.github/sync-files.yaml

@@ -27,6 +27,8 @@
         sd "        with:\n" "        with:\n          local-cspell-json: .cspell.json\n" {source}
     - source: .github/workflows/sync-files.yaml
     - source: .github/workflows/update-codeowners-from-packages.yaml
+      pre-commands: |
+        sd "          auto-merge-method: squash\n" "          auto-merge-method: squash\n          global-codeowners: @autowarefoundation/autoware-core-global-codeowners" {source}
     - source: .clang-format
     - source: .clang-tidy
     - source: .markdown-link-check.json