Ensure restore_secrets.py skips GMA paths

This commit ensures that `scripts/gha/restore_secrets.py` correctly
skips processing for any GMA-related encrypted files. The existing
check `if api == "gma": continue` should prevent attempts to write
decrypted secrets to the `gma/integration_test` directory, which no
longer exists after the removal of the GMA SDK.

This submission is to confirm the CI tests against this version of the
script.

Author: google-labs-jules[bot]