chore(ci): concurrency group for integration test

Add a concurrency group for integration test workflow. Integration
tests are flaky otherwise. Workflow is now triggered automatically
without approval, but will queue up if there's other runs active
at the time.

Signed-off-by: Ville Vesilehto <ville.vesilehto@upcloud.com>

Author: thevilledev

.github/workflows/integration-test.yml

@@ -1,17 +1,21 @@
 name: integration-test
 
 on:
-  pull_request_review:
-    types: [submitted]
+  pull_request:
     paths:
       - '**.go'
       - 'go.mod'
       - 'go.sum'
       - '.github/workflows/integration-test.yaml'
+      - 'Makefile'
+  workflow_dispatch:
 
 permissions:
   contents: read
 
+concurrency:
+  group: integration-test
+
 jobs:
   integration-test:
     if: github.event.review.state == 'approved'