Evaluate auto-regenerating sdks when AutoRest Ruby generator is changed

[veronicagg]

When AutoRest Ruby generator gets updated, automatic PRs (due to swagger changes) regenerate some sdks with the latest build, though other sdks aren't regenerated. This causes ruby-sdks in master to be in somewhat a half-state, and usually gets fixed only when we manually regenerate all sdks before release. We may want to create a job that submits an automatic PR with all regenerated sdks when ruby generator files in autorest are changed.