Rollup merge of #94145 - ssomers:binary_heap_tests, r=jyn514

Test leaking of BinaryHeap Drain iterators

Add test cases about forgetting the `BinaryHeap::Drain` iterator, and slightly fortifies some other test cases.

Consists of separate commits that I don't think are relevant on their own (but I'll happily turn these into more PRs if desired).

diff --cc library/alloc/src/collections/binary_heap/tests.rs
Simple merge

diff --cc library/alloc/src/collections/btree/map/tests.rs
Simple merge

diff --cc library/alloc/src/collections/btree/mod.rs
Simple merge

diff --cc library/alloc/src/collections/btree/set/tests.rs
Simple merge

diff --cc library/alloc/src/collections/linked_list/tests.rs
Simple merge

diff --cc library/alloc/src/lib.rs
Simple merge