simplify scala 3 build in CI (#1486)

* simplify scala 3 build in CI

* Update scala3-build.yml

.github/workflows/scala3-build.yml

@@ -3,6 +3,7 @@ name: Build and test Pekko with Scala 3
 on:
   schedule:
     - cron: "0 0 * * *"
+  pull_request:
   workflow_dispatch:
 
 permissions: {}
@@ -18,19 +19,6 @@ jobs:
     runs-on: ubuntu-20.04
     if: github.repository == 'apache/pekko'
     strategy:
-      matrix:
-        command:
-          - ;testkit/test;actor-tests/test
-          - ;actor-testkit-typed/test;actor-typed-tests/test
-          - ;bench-jmh/test
-          - ;cluster/test;cluster-tools/test;cluster-typed/test;distributed-data/test;cluster-metrics/test;cluster-sharding/test;cluster-sharding-typed/test
-          - ;discovery/test;coordination/test
-          - ;persistence/test;persistence-shared/test;persistence-query/test;persistence-typed/test;persistence-testkit/test;persistence-tck/test;persistence-typed-tests/test
-          - ;pki/test;slf4j/test
-          - ;serialization-jackson/test
-          - ;stream/test;stream-testkit/test;stream-tests/test;stream-typed/test;stream-typed-tests/test
-          - ;stream-tests-tck/test
-          - ;remote/test;remote-tests/test;protobuf-v3/test
       fail-fast: true
     steps:
       - name: Checkout
@@ -66,20 +54,4 @@ jobs:
           -Dmultinode.Xms256M \
           -Dmultinode.Xmx256M \
           -Dmultinode.XX:+AlwaysActAsServerClassMachine \
-          "++ 3.x ${{ matrix.command }}"
-
-      # comment out email actions until we have an email address to use (and we need to get INFRA to whitelist dawidd6/action-send-mail)
-      #- name: Email on failure
-      #  if: ${{ failure() }}
-      #  uses: dawidd6/action-send-mail@v3
-      #  with:
-      #    server_address: smtp.gmail.com
-      #    server_port: 465
-      #    username: ${{secrets.MAIL_USERNAME}}
-      #    password: ${{secrets.MAIL_PASSWORD}}
-      #    subject: "Failed: ${{ github.workflow }} / ${{ github.job }}"
-      #    to: [email protected]
-      #    from: Akka CI (GHActions)
-      #    body: |
-      #      Job ${{ github.job }} in workflow ${{ github.workflow }} of ${{github.repository}} failed!
-      #      https://github.com/${{github.repository}}/actions/runs/${{github.run_id}}
+          "++ 3.x test"