[libc++][test] Mark ranges.transform.pass.cpp UNSUPPORTED for AIX

The `ranges.transform.pass.cpp` often times out on CI for AIX (32-bit and 64-bit)
only. Mark the test as `UNSUPPORTED` for `AIX` for now. It should be looked into in
the future.

Differential Revision: https://reviews.llvm.org/D127051