This fixes the two points in the note at the top of the
flavors page:
1. The policy rule in the first bullet was old so it's updated.
2. As of Ifa4e9cdfbbac1a1d4bf28679b24a17b13f637ddd in Pike,
Horizon no longer allows you to 'edit' a flavor by default.
Rather than try to explain historical bad behavior and the
new default behavior in the Dashboard, the second bullet is
simply removed.
Closes-Bug: #1715995
Change-Id: I372bf1e159d1db32461f843bd94c453d2e7df8d2
a9f11002cc