run e2e only when frontend label is here

.github/workflows/run_tests.yml

@@ -2,6 +2,8 @@ name: "_Tests"
 
 on:
   workflow_call:
+  pull_request:
+    types: [labeled, opened, synchronize]
 
 defaults:
   run:
@@ -71,6 +73,7 @@ jobs:
 
   e2e:
     runs-on: ubuntu-latest
+    if: contains(join(github.event.pull_request.labels.*.name, ','), 'frontend')
     strategy:
       matrix:
         shard: [1/5, 2/5, 3/5, 4/5, 5/5]