Skip repo-specific CI on forks. (#13410)

This will avoid pestering users with failed workflow run messages for
workflows that should not even be running in their repos.

.github/workflows/add-to-project.yml

@@ -9,6 +9,7 @@ on:
 jobs:
   add-to-project:
     name: Add issue to project
+    if: github.repository == 'netdata/netdata'
     runs-on: ubuntu-latest
     steps:
       - name: Add issues to Agent project board

.github/workflows/cloud_regression.yml

@@ -13,6 +13,7 @@ on:
 jobs:
   trigger_cloud_regression_tests:
     runs-on: ubuntu-latest
+    if: github.repository == 'netdata/netdata'
     steps:
       - name: Evaluate workflow dispatch parameters
         env:

.github/workflows/packagecloud.yml

@@ -10,7 +10,7 @@ jobs:
   cleanup:
     name: PackageCloud Cleanup
     runs-on: ubuntu-latest
-    if: always()
+    if: github.repository == 'netdata/netdata'
     strategy:
       fail-fast: false
       matrix: