swift

48830133 - [Concurrency] Avoid dowgrading diagnostics multiple times

[Concurrency] Avoid dowgrading diagnostics multiple times Unify `warn` + `limitBehavior` into a single call to make sure that diagnostic doesn't get downgraded multiple times because that could affect how diagnostics are tracked. (cherry picked from commit 1649b5ec45ef1f08fbdcdb923aa95ac831a99911)