[libc++] Revert "Compile MSAN/TSAN failing test with -O1 (#73555)"

This reverts commit 61aef97, which
broke the CI on GCC.

Author: ldionne

libcxx/test/std/containers/sequences/deque/deque.modifiers/insert_iter_iter.pass.cpp

@@ -9,10 +9,6 @@
 // REQUIRES: long_tests
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
 
-// This test chokes on the sanitizers during CI runs. It appears we can address most of this by simply enabling optimizations.
-// ADDITIONAL_COMPILE_FLAGS(msan): -O1
-// ADDITIONAL_COMPILE_FLAGS(tsan): -O1
-
 // <deque>
 
 // template <class InputIterator>

libcxx/test/std/numerics/rand/rand.dist/rand.dist.bern/rand.dist.bern.negbin/eval.pass.cpp

@@ -8,10 +8,6 @@
 //
 // REQUIRES: long_tests
 
-// This test is super slow, in particular with msan or tsan. In order to avoid timeouts and to
-// spend less time waiting for this particular test to complete we compile with optimizations.
-// ADDITIONAL_COMPILE_FLAGS: -O1
-
 // <random>
 
 // template<class IntType = int>