fix(ci): Change how FIREBASE_CI is enabled (#15364)

Author: ncooke3

.github/workflows/auth.yml

@@ -141,5 +141,6 @@ jobs:
       platforms: '[ "ios", "tvos --skip-tests", "macos --skip-tests", "watchos --skip-tests" ]'
       flags: '[ "--use-static-frameworks" ]'
       setup_command: scripts/configure_test_keychain.sh
+      ignore_deprecation_warnings: true
     secrets:
       plist_secret: ${{ secrets.GHASecretsGPGPassphrase1 }}

.github/workflows/common_cocoapods_cron.yml

@@ -46,8 +46,11 @@ on:
         required: false
         default: "macos-15"
 
-env:
-  FIREBASE_CI: true
+      # Whether to ignore deprecation warnings by setting FIREBASE_CI.
+      ignore_deprecation_warnings:
+        type: boolean
+        required: false
+        default: false
 
 jobs:
   cron-job:
@@ -67,6 +70,9 @@ jobs:
       run: scripts/setup_bundler.sh
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ inputs.xcode }}.app/Contents/Developer
+    - name: Set FIREBASE_CI, if needed.
+      if: inputs.ignore_deprecation_warnings == true
+      run: echo "FIREBASE_CI=true" >> $GITHUB_ENV
     - name: Run setup command, if needed.
       if: inputs.setup_command != ''
       env: