feat: [recaptchaenterprise] add RetrieveLegacySecretKey method#8571

gcf-merge-on-green[bot] merged 2 commits intomaingoogleapis/google-cloud-java:mainfrom

owl-bot-copy-java-recaptchaenterprisegoogleapis/google-cloud-java:owl-bot-copy-java-recaptchaenterpriseCopy head branch name to clipboard