Configure git hooksPath before building on runners

On runners git hooks aren't used, but we now configure them anyway to
avoid logspam on each bazel invocation since workspace-status.sh checks
whether githooks are in place.

.github/workflows/test.yml

@@ -108,6 +108,9 @@ jobs:
           build:asan --config=limit-storage
           build:debug --config=limit-storage
           EOF
+      - name: Configure git hooks
+        # Configure git to quell an irrelevant warning for runners (they never commit / push).
+        run: git config core.hooksPath githooks
       - name: Bazel build
         # timestamps are no longer being added here, the GitHub logs include timestamps (Use
         # 'Show timestamps' on the web interface)