GitHub Actions: reduce PR action count & fix MontiVerse branch

Signed-off-by: Alex Lüpges <luepges@se-rwth.de>

.github/workflows/gradle_mc.yml

@@ -10,7 +10,7 @@ on:
   push: # run this test pipeline on every push
     paths-ignore:
       - "*.md"
-  pull_request: # and pull request
+  pull_request: # and pull request  (Note: We can skip pull request events IFF the PR is not done from a fork)
     paths-ignore:
       - "*.md"
   repository_dispatch: # and on request of upstream projects
@@ -28,6 +28,7 @@ permissions:
 
 jobs:
   build-generator: # Note: Build-Cache may not work yet
+    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name != github.event.pull_request.base.repo.full_name # do not run duplicate jobs on PRs
     runs-on: ubuntu-latest
     steps:
       - name: Checkout project sources
@@ -134,7 +135,7 @@ jobs:
 
   # Run the MontiVerse pipeline (tests this change on a suite of projects)
   trigger-montiverse:
-    if: ${{ !github.event.client_payload && github.ref != 'refs/heads/dev'}} # do not run on upstream-changes or default branch
+    if: github.event_name == 'pull_request' # only run on PRs
     runs-on: ubuntu-latest
     needs: [ build-mc ]
     steps:
@@ -147,7 +148,7 @@ jobs:
           id: '91803'  # montiverseci project id
           ref: 'main'
           # TODO: Include entire git path here instead (due to PRs)
-          variables: '{"MONTICORE_BRANCH":"${{github.ref}}"}'
+          variables: '{"MONTICORE_BRANCH":"${{github.event.pull_request.head.ref }}", "MONTICORE_PROJECT":"${{ github.event.pull_request.head.repo.full_name }}"}'
 
         # TODO: Proper message in PRs (turn the MontiVerse into a GitHub Action?)?