uplift_beta rule message should not suggest wontfix-ing bugs that are `tracking_firefox_beta +`

[dveditz]

The uplift_beta rule tells developers that their patch landing in nightly and beta is marked affected, and asks them "is this bug important enough to require an uplift?" and suggests they mark the beta status field "wontfix" if it is not. This is wrong if the bug is already being tracked by Release Management (cf_tracking_firefox_beta set to +). If the developer feels the uplift would be a mistake they need to talk to release management and come to a shared agreement.

If the bug doesn't have an explicit tracking "+" or "-" but has a severity of S1 or S2 you probably also don't want to suggest the developer wontfix it without talking to someone about it first.