`#[global_allocator]` and `#[thread_local]` should not be usable together on the same `static`

[repnop]

As per #85487 (comment), using both #[global_allocator] and #[thread_local] is currently allowed but should not be since the Global allocator is always Sync + Send which means that even if the type implementing GlobalAlloc is neither, allocations using the default Global allocator can be sent between threads which is unsound as they would be deallocated in a different allocator.

[memoryruins]

@rustbot label: T-libs, A-allocators, F-thread_local

[zhi-ping]

I'd like to work on this issue. @rustbot claim

[Fayti1703]

@rustbot claim