Rollup merge of #124387 - workingjubilee:use-raw-pointers-in-thread-locals, r=joboet

thread_local: be excruciatingly explicit in dtor code

Use raw pointers to accomplish internal mutability, and clearly split references where applicable. This reduces the likelihood that any of these parts are misunderstood, either by humans or the compiler's optimizations.

Fixes #124317

r? ``@joboet``

Author: matthiaskrgr