ci: run 'make check' as reusable workflow (#17600)

Some of the paths ignored by `test-core.yaml` need to be checked by
`make check`. The `checks.yaml` workflow run on these paths and can also
be used as a reusable workflow.

.github/workflows/checks.yaml

@@ -0,0 +1,36 @@
+# Run 'make check' on paths ignored by test-core.yaml.
+name: Run checks
+on:
+  pull_request:
+    paths:
+      - 'demo/**'
+      - 'e2e/terraform/**'
+      - 'terraform/**'
+      - 'website/**'
+  push:
+    branches:
+      - 'main'
+      - 'release/**'
+    paths:
+      - 'demo/**'
+      - 'e2e/terraform/**'
+      - 'terraform/**'
+      - 'website/**'
+  workflow_call:
+
+jobs:
+  checks:
+    runs-on: ubuntu-22.04
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab # v3.5.2
+        with:
+          fetch-depth: 0 # needs tags for checkproto
+      - uses: hashicorp/setup-golang@v1
+      - name: Run make check
+        run: |
+          make missing
+          make bootstrap
+          make check
+permissions:
+  contents: read

.github/workflows/test-core.yaml

@@ -57,19 +57,8 @@ jobs:
           make tidy
           make bootstrap
   checks:
+    uses: ./.github/workflows/checks.yaml
     needs: [mods]
-    runs-on: ubuntu-22.04
-    timeout-minutes: 10
-    steps:
-      - uses: actions/checkout@8e5e7e5ab8b370d6c329ec480221332ada57f0ab # v3.5.2
-        with:
-          fetch-depth: 0 # needs tags for checkproto
-      - uses: hashicorp/setup-golang@v1
-      - name: Run make check
-        run: |
-          make missing
-          make bootstrap
-          make check
   compile:
     needs: [mods, checks]
     strategy:
@@ -129,4 +118,3 @@ jobs:
           sudo -E env "PATH=$PATH" make test-nomad
 permissions:
   contents: read
-