[LifetimeSafety] Remove confidence tracking (#182709)
Removed the confidence level tracking system from the lifetime safety
analysis, simplifying the implementation by eliminating the distinction
between "definite" and "maybe" lifetime violations.
The confidence level system was marked as deprecated in the TODO comment
and was no longer being used to differentiate between strict and
permissive warnings. Removing this complexity simplifies the codebase
while maintaining the core lifetime safety analysis functionality. The
change eliminates the distinction between "must-be-live" and
"maybe-be-live" states, treating all detected lifetime violations
uniformly.
