[MGMT] avoid automatically skip revapi check for preview lib

> Alternatively, can we keep the revapi check always on and add suppressions for only those releases that need it? If we skip the check for all preview releases, the breaking change can be a surprise during GA release. We can let the library owners know that there is a breaking change in the preview itself to prepare them for approvals or make necessary customizations to prevent breaks rather than waiting for GA version change.

> We can. Just potentially lots of manual efforts. Given self-service, service can do a single click on "re-generate SDK" and refresh the PR and then any manual change would be gone.