Add bug_map as a cached property for LandingsRiskReportGenerator

[suhaibmujahid]

As a follow-up, what do you think about adding bug_map as a cached property (i.e., @cached_property)? In that way, we do not need to pass it with the function calls.

Originally posted by @suhaibmujahid in #5052 (comment)

[Probatio-Diabolica]

Hi @suhaibmujahid !

While turning bug_map into a @cached_property , I saw it depends on variables like bugs, meta_bugs, etc., which are local to go().

Would it be okay to move those to instance attributes (like self.bugs) so the property works as expected?