[lldb] Keep the existing behavior for untrusted dSYMs (#190407)
This patch does two thing:
- It reverts to the previous behavior of warning for untrusted dSYMs.
- It includes whether a dSYM is trusted or untrusted in the warning
output.
My reasoning is that there's no tooling for automatically signing dSYMs
and therefore we shouldn't change the behavior until this is more
common. The inclusion of whether the dSYM is signed or not is the first
step towards advertising the existence of the feature.
This now also means the release note I added in #189444 is correct
(again).