Introduce a seperate message for stabilization reasons

In some cases, it might be desirable to have seperate list for
protection reasons and stabilization reasons.  The default list is,
however, the same, so by default the stabilization-dropdown message is
empty, which causes it to fall back to protect-dropdown.

Bug: 59635
Change-Id: I8ba01ff715694899cd974cf45b627ab20ca99e55