[no-ticket] Enable activate-build-cache-for-xcode for all firefox build steps (#30413)

Author: clarmso

bitrise.yml

@@ -147,6 +147,7 @@ workflows:
         run_if: '{{getenv "SSH_RSA_PRIVATE_KEY" | ne ""}}'
     - [email protected]:
         is_always_run: true
+    - activate-build-cache-for-xcode@0: {}
     - xcode-build-for-test@3:
         inputs:
         - scheme: Fennec