[NFC][libc++] Update comments to reflect changes in ASan

ASan capabilities were extended, but some comments were not updated and describe old behavior. This commit updates outdated comments, which I found.
Mentioned changes are:
- All allocators in containers (`std::vector` and `std::deque`; D146815 D136765) are supported, but it's possible to turn off annotations for a specific allocator (D145628).
- Buffers don't have to be aligned (D132522).

Reviewed By: #libc, philnik

Differential Revision: https://reviews.llvm.org/D156155

libcxx/include/deque

@@ -968,7 +968,12 @@ public:
    };
 
 // The following functions are no-ops outside of AddressSanitizer mode.
-// We call annotations only for the default Allocator.
+// We call annotations for every allocator, unless explicitly disabled.
+//
+// To disable annotations for a particular allocator, change value of
+// __asan_annotate_container_with_allocator to false.
+// For more details, see the "Using libc++" documentation page or
+// the documentation for __sanitizer_annotate_contiguous_container.
 #if !defined(_LIBCPP_HAS_NO_ASAN) && _LIBCPP_CLANG_VER >= 1600
     // TODO LLVM18: Remove the special-casing
     _LIBCPP_HIDE_FROM_ABI void __annotate_double_ended_contiguous_container(

libcxx/include/vector

@@ -840,9 +840,12 @@ private:
     inline void __emplace_back_slow_path(_Args&&... __args);
 
     // The following functions are no-ops outside of AddressSanitizer mode.
-    // We call annotatations only for the default Allocator because other allocators
-    // may not meet the AddressSanitizer alignment constraints.
-    // See the documentation for __sanitizer_annotate_contiguous_container for more details.
+    // We call annotations for every allocator, unless explicitly disabled.
+    //
+    // To disable annotations for a particular allocator, change value of
+    // __asan_annotate_container_with_allocator to false.
+    // For more details, see the "Using libc++" documentation page or
+    // the documentation for __sanitizer_annotate_contiguous_container.
 #ifndef _LIBCPP_HAS_NO_ASAN
     _LIBCPP_CONSTEXPR_SINCE_CXX20
     void __annotate_contiguous_container(const void *__beg, const void *__end,