test(lib-injection): fix the version of tests used

We've been changing the tests quite a bit lately which has led to CI
breakage. It makes sense, since we backport so much, to fix the version
so that CI remains stable.

This particular change, changed the scripts used to run the tests.

.github/workflows/lib-injection.yml

@@ -38,9 +38,9 @@ jobs:
     steps:
       - name: lib-injection test runner
         id: lib-injection-test-runner
-        uses: DataDog/system-tests/lib-injection/runner@main
+        uses: DataDog/system-tests/lib-injection/runner@b3ca75b6ce109a349f7390a9f111e6b3ef3c97ef
         with:
           docker-registry: ghcr.io
           docker-registry-username: ${{ github.repository_owner }}
           docker-registry-password: ${{ secrets.GITHUB_TOKEN }}
-          test-script: ./lib-injection/run-lib-injection.sh
+          test-script: ./lib-injection/run-manual-lib-injection.sh