Remove more static mut refs from UI tests

[NotPppp1116]

Replace additional static mut counters and order logs in UI tests with atomic values.

This removes 11 more stale #![allow(static_mut_refs)] allowances from tests that only need simple observable counters or drop-order logs. The tests intentionally exercising static mut semantics are left unchanged.

Validation:

./x test tests/ui/binding/order-drop-with-match.rs tests/ui/drop/issue-48962.rs tests/ui/array-slice-vec/slice.rs tests/ui/array-slice-vec/slice-panic-1.rs tests/ui/array-slice-vec/slice-panic-2.rs tests/ui/drop/generic-drop-trait-bound-15858.rs tests/ui/drop/drop-struct-as-object.rs tests/ui/methods/method-self-arg.rs tests/ui/methods/method-self-arg-trait.rs tests/ui/self/where-for-self.rs tests/ui/traits/impl.rs --force-rerun

Result: 11 passed, 0 failed.

[rustbot]

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[fee1-dead]

I'm not a big fan of using atomics in some of these tests that don't have threading. Some of our targets don't have atomics and this makes some tests that are otherwise applicable fail on those targets. Raw pointers could just work. Also for some threaded examples consider using thread scope.

View changes since this review

[rustbot]

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