Disable certain actions from running on forks (#23747)

* Disable certain actions from running on forks

* Address some feedback

* Check for forks in build-docker job

.github/workflows/artifacts.yml

@@ -9,7 +9,7 @@ jobs:
   upload-s3:
     name: cd/Upload artifacts to S3
     runs-on: ubuntu-22.04
-    if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
+    if: github.repository_owner == 'mattermost' && github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
     steps:
       - name: cd/Configure AWS
         uses: aws-actions/configure-aws-credentials@07c2f971bac433df982ccc261983ae443861db49 # v1-node16
@@ -36,7 +36,7 @@ jobs:
     name: cd/Build and push docker image
     needs: upload-s3
     runs-on: ubuntu-22.04
-    if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
+    if: github.repository_owner == 'mattermost' && github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
     steps:
       - name: cd/Login to Docker Hub
         uses: docker/login-action@3da7dc6e2b31f99ef2cb9fb4c50fb0971e0d0139 # v2.1.0