JIT: Assertion prop does unnecessary bitvector copying

[JosephTremoulet]

See #9773 (comment) and the changes in optComputeAssertionGen in dotnet/coreclr#9773 to populate jumpDestGen using fewer copies.
category:throughput
theme:assertion-prop
skill-level:intermediate
cost:small
impact:medium

[mikedn]

Probably the unnecessary allocation and copying doesn't have a large impact because not a lot of methods use 128/256 assertion tables (e.g. less than 1% of the crossgened corelib methods).

[kunalspathak]

Removing JitUntriaged, now that it is tracked in #74671