Update schema verification tools to ignore temporary lack of PUBLIC availability of schema file when pushing the release.

[jsuereth]

We should update the verify schemas shell script so that if a schema is not available publicly, it does not automatically fail, but we do get a warning if the schema file in our repository every deviates from the publicly available schema file.

For the 1.21.0 release we disabled the check so we can cut a branch that will be merged into the website.