Updating regex for short-form client IDs

Client IDs can take many forms, however the first 10 digits are the ones that count but there can . For example:

* ID.apps.googleusercontent.com (standard, web)
* ID (short form)
* ID-devicestring.apps.googleusercontent.com (Android)
* ID-devicestring.apps.googleusercontent.com (iOS)

Our existing regular expression will correctly match the patterns except for in the short form. This update adds a simpler regex to match all these cases.