Merge pull request #30578 from andreaTP/conditional-scheduled

Run scheduled jobs only on main repo

.github/workflows/nightly-builds.yml

@@ -9,6 +9,7 @@ jobs:
   nightly-cluster-metrics-sigar:
     name: Akka Cluster Metrics Test with Sigar
     runs-on: ubuntu-20.04
+    if: github.repository == ‘akka/akka’
     steps:
 
       - name: Checkout
@@ -63,6 +64,7 @@ jobs:
   jdk-nightly-tests:
     name: JDK ${{ matrix.jdkVersion }} / Scala ${{ matrix.scalaVersion }}
     runs-on: ubuntu-20.04
+    if: github.repository == ‘akka/akka’
     strategy:
       matrix:
         # No need to specify the full Scala version. Only the Scala binary version