infra: Broaden symbolcollision.yml workflow triggers (#15657)

Author: ncooke3

.github/workflows/symbolcollision.yml

@@ -20,7 +20,7 @@ concurrency:
 jobs:
   installation-test:
     # Don't run on private repo unless it is a PR.
-    if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
+    if: github.repository == 'Firebase/firebase-ios-sdk' || github.event_name == 'pull_request'
     runs-on: macos-15
 
     steps: