Revert "Allow flags to add metadata directly in code."

Revert submission 23727772-b279054964-flag-api-udc-qpr-dev

Reason for revert: b/290929382

Reverted changes: /q/submissionid:23727772-b279054964-flag-api-udc-qpr-dev

Change-Id: I328c83d38cfc4afd03dcba759234777db41bb4a8
6 files changed