Revert "[libc++] Simplify the implementation of reserve() and shrink_to_fit() (#113453)"

This reverts commit d648eed5899c4be10f1f7866eebef2bc171e673f. Breaks
anything that relies on sized deallocation, e.g. asan and tcmalloc.

GitOrigin-RevId: 59f57be94f38758616b1339b293b43af845571af
1 file changed