Rollup merge of #150065 - is57primenumber:add-slice-cse-test, r=Mark-Simulacrum

add CSE optimization tests for iterating over slice

This PR is regression test for issue rust-lang/rust#119573.
This PR introduces a new regression test to verify a critical optimization known as Common Subexpression Elimination (CSE) is correctly applied during various slice iteration patterns.

Author: matthiaskrgr