Revert "Auto merge of rust-lang#51165 - SimonSapin:opt2, r=alexcrichton"

This reverts commit 524ad9b, reversing
changes made to 59c0f59.

Author: kennytm

src/Cargo.toml

@@ -40,13 +40,6 @@ members = [
   "tools/rls/test_data/workspace_symbol",
 ]
 
-# Curiously, libtest will segfault if compiled with opt-level=3
-# with some versions of XCode: https://github.com/rust-lang/rust/issues/50867
-[profile.release]
-opt-level = 2
-[profile.bench]
-opt-level = 2
-
 # These options are controlled from our rustc wrapper script, so turn them off
 # here and have them controlled elsewhere.
 [profile.dev]