Auto merge of #89144 - sexxi-goose:insig_stdlib, r=nikomatsakis

Auto merge of #89144 - sexxi-goose:insig_stdlib, r=nikomatsakis

2229: Mark insignificant dtor in stdlib

I looked at all public [stdlib Drop implementations](https://doc.rust-lang.org/stable/std/ops/trait.Drop.html#implementors) and categorized them into Insigificant/Maybe/Significant Drop.

Reasons are noted here: https://docs.google.com/spreadsheets/d/19edb9r5lo2UqMrCOVjV0fwcSdS-R7qvKNL76q7tO8VA/edit#gid=1838773501

One thing missing from this PR is tagging HashMap as insigificant destructor as that needs some discussion.

r? `@Mark-Simulacrum`

cc `@nikomatsakis`