Set FIREBASE_CI for release and prerelease CI (#14394)

.github/workflows/prerelease.yml

@@ -9,6 +9,9 @@ on:
     # Run every day at 9pm (PST) - cron uses UTC times
     - cron:  '0 5 * * *'
 
+env:
+  FIREBASE_CI: true
+
 concurrency:
     group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
     cancel-in-progress: true

.github/workflows/release.yml

@@ -11,6 +11,9 @@ on:
     # Run every day at 9pm (PST) - cron uses UTC times
     - cron:  '0 5 * * *'
 
+env:
+  FIREBASE_CI: true
+
 concurrency:
     group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
     cancel-in-progress: true