feat(devservices): Add devservices config validation job (#4426)

This validation job will only run if files are changed in the
devservices/ directory or the .github/workflows/ci.yml has been changed.
It will ensure that the config files that live in the relay devservices
directory actually work, preventing potential breakages for devservices
across repos that depend on snuba if invalid configs are merged.

Composite action used:
https://github.com/getsentry/action-validate-devservices-config

#skip-changelog

.github/workflows/ci.yml

@@ -75,6 +75,24 @@ jobs:
       - name: Run Clippy
         run: cargo clippy --workspace --all-targets --no-deps -- -D warnings
 
+  devservices-files-changed:
+    name: detect what files changed
+    runs-on: ubuntu-24.04
+    timeout-minutes: 3
+    outputs:
+      devservices-files-changed: ${{ steps.changes.outputs.devservices-files-changed }}
+    steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      - uses: dorny/paths-filter@de90cc6fb38fc0963ad72b210f1f284cd68cea36 # v3.0.2
+        name: Check for file changes
+        id: changes
+        with:
+          token: ${{ github.token }}
+          filters: |
+            devservices-files-changed:
+              - 'devservices/**'
+              - '.github/workflows/ci.yml'
+
   test:
     timeout-minutes: 20
     strategy:
@@ -628,3 +646,15 @@ jobs:
           image_url: ghcr.io/getsentry/relay:${{ github.event.pull_request.head.sha || github.sha }}
           docker_repo: getsentry/relay
           docker_password: ${{ secrets.DOCKER_HUB_RW_TOKEN }}
+
+  validate-devservices-config:
+      runs-on: ubuntu-24.04
+      needs: devservices-files-changed
+      if: ${{ needs.devservices-files-changed.outputs.devservices-files-changed == 'true' }}
+      steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+        name: Checkout repository
+      - uses: getsentry/action-validate-devservices-config@6477ef1e9c96e456bfad726006e731f89fcd81db
+        name: Validate devservices config
+        with:
+          requirements-file-path: requirements-dev.txt