test(lib-injection): fix the version of tests used [backport #5062 to 1.8] (#5064)

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.

## Checklist

- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/contributing.html#Release-Note-Guidelines)
are followed.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).


## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.

Author: Kyle-Verhoog

.github/workflows/lib-injection.yml

@@ -66,12 +66,12 @@ jobs:
       DOCKER_REGISTRY_IMAGES_PATH: ghcr.io/datadog
       DOCKER_IMAGE_TAG: ${{ github.sha }}
       BUILDX_PLATFORMS: linux/amd64
-    steps:    
-    
+    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 }}
+          docker-registry-password: ${{ secrets.GITHUB_TOKEN }}
+          test-script: ./lib-injection/run-manual-lib-injection.sh