inference: regression in `BaseBenchmarks.InferenceBenchmarks.many_local_vars` benchmark from #46010

[aviatesk]

#46010 seems to have introduced a significant regression in cases like BaseBenchmarks.InferenceBenchmarks.many_local_vars.

There are some observation and discussion happening here:

• benchmark result: https://github.com/JuliaLang/julia/commit/dd375e199b6f17d5a14bbf1339d8a74cf5a3bb62#commitcomment-82877581
• profiling: https://github.com/JuliaLang/julia/commit/dd375e199b6f17d5a14bbf1339d8a74cf5a3bb62#commitcomment-83236324