Rollup merge of #131085 - RalfJung:miri-slow-test, r=tgross35

make test_lots_of_insertions test take less long in Miri

This is by far the slowest `std` test in Miri, taking >2min in https://github.com/rust-lang/miri-test-libstd CI. So let's make this `count` smaller. The runtime should be quadratic in `count` so reducing it to around 2/3 of it's previous value should cut the total time down to less than half -- making it still the slowest test, but by less of a margin. (And this way we still insert >64 elements into the HashMap, in case that power of 2 matters.)

library/std/src/collections/hash/map/tests.rs

@@ -274,7 +274,7 @@ fn test_lots_of_insertions() {
     for _ in 0..loops {
         assert!(m.is_empty());
 
-        let count = if cfg!(miri) { 101 } else { 1001 };
+        let count = if cfg!(miri) { 66 } else { 1001 };
 
         for i in 1..count {
             assert!(m.insert(i, i).is_none());