UCT/GTEST: Fixed multiple tests for gdr_copy transport - v1.17.x

[iyastreb]

What

This is a double commit of #9840

This is the fix for RM#3873368.
The issue is always reproducible on rock, when building and running UCX with the following modules:

module load hpcx-env
module load hpcx-env/cuda
module load hpcx-env/gdrcopy

With gdr_copy MD configured, memory registration fails in several test suites:

• 3 tests in test_md
• 2 tests in uct_test
• test_uct_loopback_cuda

The root cause was always the same: CUDA memory of arbitrary size was allocated, and then this memory is registered with uct_md_mem_reg without any alignment. However this does not work for gdr_copy transport, because it's required to register memory aligned by GPU_PAGE_SIZE (64k in this case).

I fixed the memory registration in all those places the same way it's done in ucp_mm module: by alignment using ucs_align_ptr_range API